Clarify lookups of Microsoft IdP attributes (#47597)

Closes #19118

Edit the Role Reference, Azure AD, and AD FS guides to explain that you
must use bracket notation to look up Azure AD and AD FS attributes in
roles.

docs/pages/admin-guides/access-controls/sso/adfs.mdx

@@ -130,9 +130,10 @@ The login
 <nobr>`{{external["http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname"]}}`</nobr>
 configures Teleport to look at the
 `http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname`
-ADFS claim and use that field as an allowed login for each user. Note the
-double quotes (`"`) and square brackets (`[]`) around the claim name—these are
-important.
+attribute and use that field as an allowed login for each user. Since the name
+of the attribute contains characters besides letters, numbers, and underscores,
+you must use double quotes (`"`) and square brackets (`[]`) around the name of
+the attribute.
 
 ## Step 3/3. Create a SAML connector
 

docs/pages/admin-guides/access-controls/sso/azuread.mdx

@@ -173,10 +173,7 @@ $ tctl create -f azure-connector.yaml
 Create a Teleport role resource that will use external username data from the
 Azure AD connector to determine which Linux logins to allow on a host.
 
-Users with the following `dev` role are only allowed to log in to nodes with
-the `access: relaxed` Teleport label. They can log in as either `ubuntu` or a
-username that is passed in from the Azure AD connector. Users with this role can't
-obtain admin access to Teleport.
+Create a file called `dev.yaml` with the following content:
 
 ```yaml
 kind: role
@@ -187,12 +184,27 @@ spec:
   options:
     max_session_ttl: 24h
   allow:
-    logins: [ "{{external.username}}", ubuntu ]
+    # only allow login as either ubuntu or the 'windowsaccountname' claim
+    logins: [ '{{external["http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname"]}}', ubuntu ]
     node_labels:
       access: relaxed
 ```
 
-Replace `ubuntu` with the Linux login available on your servers.
+Users with the `dev` role are only allowed to log in to nodes with the `access:
+relaxed` Teleport label. They can log in as either `ubuntu` or a username that
+is passed in from the Azure AD connector using the `windowsaccountname`
+attribute.
+
+The login
+<nobr>`{{external["http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname"]}}`</nobr>
+configures Teleport to look at the
+`http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname`
+attribute and use that field as an allowed login for each user. Since the name
+of the attribute contains characters besides letters, numbers, and underscores,
+you must use double quotes (`"`) and square brackets (`[]`) around the name of
+the attribute.
+
+Create the role:
 
 ```code
 $ tctl create dev.yaml

docs/pages/reference/access-controls/roles.mdx

@@ -558,7 +558,6 @@ logins:
    - '{{external["http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname"]}}'
 ```
 
-
 In role templates, you can refer to these variables using the following two
 formats, where `trait` is the name of the trait:
 
@@ -570,7 +569,14 @@ attribute or OIDC claim called `trait`.
 
 You can specify an external trait in dot syntax if it begins with a letter and
 contains only letters, numbers, and underscores. Otherwise, you must use bracket
-syntax to specify a trait.
+syntax to specify a trait. 
+
+When using Azure AD or ADFS as your IdP, you must use bracket notation, as these
+IdPs assign attribute keys to URLs such as the following:
+
+```text
+http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname
+```
 
 Common examples of external traits available through an identity provider
 include the following: