Clarify what type of resource can have a feed

src/docs/docs/api-services/feed-discovery.md

@@ -12,8 +12,23 @@ The feed discovery service, as its name states, discovers the feed URL from a bl
 
 ### Get feeds URL from a blog URL
 
-Find any feed URLs accessible from a blog URL. To be able to use this service, you need to
-be authenticated. See more on [Authentication and Authorization](./auth.md) for details.
+Find any feed URLs accessible from a resource URL. The type of resources that can
+have a feed may be:
+
+- YouTube channels,
+- Twitch channels,
+- Blogs (e.g. dev.to, medium.com, wordpress.org),
+- anything that can be listed in a feed, there are no limits!
+
+However, be aware that the purpose of this service in the context of Telescope
+is to find feeds for resources that Telescope can currently handle. Those include:
+
+- YouTube channels,
+- Twitch channels,
+- Blogs.
+
+To be able to use this service, you need to be authenticated. See more on
+[Authentication and Authorization](./auth.md) for details.
 
 ```
 POST /
@@ -73,7 +88,7 @@ Status: 200 OK
 Status: 400 Bad Request
 ```
 
-This could be to several reasons. For example,
+This could be due to several reasons. For example,
 
 - the `blogUrl` provided is invalid (cannot be used as a proper URL).
 - the blog itself cannot be retrieved (the blog itself was deleted or the