Rewrite the Realtime guide (#296)

Rewrite the guide about the real-time engine

.gitignore

@@ -10,3 +10,4 @@ test/bin/*
 dead_links.json
 links_failed.json
 .links_checked.json
+.vscode

src/core/1/api/essentials/notifications/index.md

@@ -83,9 +83,9 @@ The `result` object is the notification content, and it has the following struct
 
 ---
 
-## User events
+## User Notification
 
-User notifications about users are triggered by the following events:
+User notifications are triggered by the following events:
 
 - A user subscribes to the same room
 - A user leaves that room
@@ -138,7 +138,7 @@ The `result` object is the notification content, and it has the following struct
 
 ---
 
-## Server events
+## Server Notification
 
 Server notifications are triggered by global events, and they are sent to all of a client's subscriptions at the same time.
 

src/core/1/api/essentials/volatile-data/index.md

@@ -76,8 +76,8 @@ There is one special case, where volatile data are stored by Kuzzle for a later
 
 Volatile data passed to a new subscription query are used two times by Kuzzle:
 
-- if the new subscription triggers [user notifications](/core/1/api/essentials/notifications#user-events-default), its volatile data are included into those
-- if that subscription is cancelled, whether because of a call to [realtime:unsubscribe](/core/1/api/controllers/realtime/unsubscribe/), or after the user disconnects: the volatile data provided **at the time of the subscription** are once again copied into user notifications triggered by that event
+- if the new subscription triggers [user notifications](/core/1/api/essentials/notifications#user-notification-default), its volatile data are included into those
+- if that subscription is cancelled, whether because of a call to [realtime:unsubscribe](/core/1/api/api-reference/controller-realtime/unsubscribe/), or after the user disconnects: the volatile data provided **at the time of the subscription** are once again copied into user notifications triggered by that event
 
 This allows other real-time subscribers to get context information about a user joining or leaving the same subscription as them.
 

src/sdk/cpp/1/essentials/realtime-notifications/index.md

@@ -8,7 +8,7 @@ order: 100
 
 # Notifications
 
-The [realtime:subscribe](/sdk/cpp/1/controllers/realtime/) method takes a listener of type `kuzzleio::NotificationListener`.  
+The [realtime:subscribe](/sdk/cpp/1/controllers/realtime/) method takes a listener of type `kuzzleio::NotificationListener`.
 That listener is called with a `const kuzzleio::notification_result*` argument, pointing to an object whose content depends on the type of notification received.
 
 ## Document & messages
@@ -38,7 +38,7 @@ The `kuzzleio::notification_content` struct has the following properties for doc
 
 ## User
 
-These `kuzzleio::notification_result` represent [user events](/core/1/api/essentials/notifications#user-events-default).
+These `kuzzleio::notification_result` represent [user events](/core/1/api/essentials/notifications#user-notification-default).
 
 | Property     | Type                                        | Description                                                                                           |
 | ------------ | ------------------------------------------- | ----------------------------------------------------------------------------------------------------- |

src/sdk/go/1/essentials/realtime-notifications/index.md

@@ -37,7 +37,7 @@ The `Result` property has the following structure for document notifications & m
 
 ## User
 
-These notifications represent [user events](/core/1/api/essentials/notifications#user-events-default).
+These notifications represent [user events](/core/1/api/essentials/notifications#user-notification-default).
 
 | Property     | Type                       | Description                                                                                           |
 | ------------ | -------------------------- | ----------------------------------------------------------------------------------------------------- |

src/sdk/java/1/essentials/realtime-notifications/index.md

@@ -8,7 +8,7 @@ order: 100
 
 # Notifications
 
-The [Realtime.subscribe](/sdk/java/1/controllers/realtime/subscribe/) method takes a `io.kuzzle.sdk.NotificationListener` event listener (implements the `EventListener` interface).  
+The [Realtime.subscribe](/sdk/java/1/controllers/realtime/subscribe/) method takes a `io.kuzzle.sdk.NotificationListener` event listener (implements the `EventListener` interface).
 That listener is fed with a `io.kuzzle.sdk.NotificationResult` object, whose content depends on the type of notification.
 
 Properties can be accessed with usual getters and setters.
@@ -40,7 +40,7 @@ The `io.kuzzle.sdk.NotificationContent` object has the following properties for
 
 ## User
 
-These `io.kuzzle.sdk.NotificationResult` represent [user events](/core/1/api/essentials/notifications#user-events-default).
+These `io.kuzzle.sdk.NotificationResult` represent [user events](/core/1/api/essentials/notifications#user-notification-default).
 
 | Property     | Type                              | Description                                                                                           |
 | ------------ | --------------------------------- | ----------------------------------------------------------------------------------------------------- |

src/sdk/js/6/essentials/realtime-notifications/index.md

@@ -37,7 +37,7 @@ The `result` object is the notification content, and it has the following struct
 
 ## User
 
-These notifications represent [user events](/core/1/api/essentials/notifications#user-events-default).
+These notifications represent [user events](/core/1/api/essentials/notifications#user-notification-default).
 
 | Property     | Type              | Description                                                                                           |
 | ------------ | ----------------- | ----------------------------------------------------------------------------------------------------- |
@@ -61,7 +61,7 @@ The `result` object is the notification content, and it has the following struct
 
 ## Server
 
-These notifications represent [server events](/core/1/api/essentials/notifications#server-events-default).
+These notifications represent [server events](/core/1/api/essentials/notifications#server-notification-default).
 
 | Property  | Type              | Value                                                              |
 | --------- | ----------------- | ------------------------------------------------------------------ |