Add support for Profile feature in REST Identity store (Fix #91)

docs/features/experimental/profile.md

@@ -1,12 +1,16 @@
-# Profile enhancement
-**WARNING**: Alpha feature, not officially supported. Do not use.
+# Profile
+**WARNING**: The following sub-features are considered experimental and not officially supported. Use at your own peril.
 
-This feature allows to enhance a profile query with more info than just Matrix ID and Display name, allowing for custom
-applications to retrieve custom data not currently provided by synapse, per example.
+## Public Profile enhancement
+This feature allows to enhance a public profile query with more info than just Matrix ID and Display name, allowing for
+custom applications to retrieve custom data not currently provided by synapse, per example.
 
-## Configuration
-### Reverse proxy
-#### Apache
+**WARNING**: This information can be queried without authentication as per the specification. Do not enable unless in a
+controlled environment.
+
+### Configuration
+#### Reverse proxy
+##### Apache
 ```apache
 ProxyPassMatch "^/_matrix/client/r0/profile/([^/]+)$" "http://127.0.0.1:8090/_matrix/client/r0/profile/$1"
 ```

docs/features/profile.md

@@ -0,0 +1,10 @@
+# Profile
+The profile feature does not do anything on its own and acts as a support feature for others, allowing to retrieve
+information about a user based on its Matrix ID by querying enabled [Identity stores](../stores/README.md).
+
+Currently supported:
+- Display name
+- 3PIDs
+- Roles/Groups
+
+Experimental sub-features are also available. See [the dedicated document](experimental/profile.md).