docs: update FEDERATION.md to more closely follow FEP conventions. (#28838)

FEDERATION.md

@@ -1,19 +1,35 @@
-## ActivityPub federation in Mastodon
+# Federation
+
+## Supported federation protocols and standards
+
+- [ActivityPub](https://www.w3.org/TR/activitypub/) (Server-to-Server)
+- [WebFinger](https://webfinger.net/)
+- [Http Signatures](https://datatracker.ietf.org/doc/html/draft-cavage-http-signatures)
+- [NodeInfo](https://nodeinfo.diaspora.software/)
+
+## Supported FEPs
+
+- [FEP-67ff: FEDERATION.md](https://codeberg.org/fediverse/fep/src/branch/main/fep/67ff/fep-67ff.md)
+- [FEP-f1d5: NodeInfo in Fediverse Software](https://codeberg.org/fediverse/fep/src/branch/main/fep/f1d5/fep-f1d5.md)
+- [FEP-8fcf: Followers collection synchronization across servers](https://codeberg.org/fediverse/fep/src/branch/main/fep/8fcf/fep-8fcf.md)
+- [FEP-5feb: Search indexing consent for actors](https://codeberg.org/fediverse/fep/src/branch/main/fep/5feb/fep-5feb.md)
+
+## ActivityPub in Mastodon
 
 Mastodon largely follows the ActivityPub server-to-server specification but it makes uses of some non-standard extensions, some of which are required for interacting with Mastodon at all.
 
-Supported vocabulary: https://docs.joinmastodon.org/spec/activitypub/
+- [Supported ActivityPub vocabulary](https://docs.joinmastodon.org/spec/activitypub/)
 
 ### Required extensions
 
-#### Webfinger
+#### WebFinger
 
 In Mastodon, users are identified by a `username` and `domain` pair (e.g., `Gargron@mastodon.social`).
 This is used both for discovery and for unambiguously mentioning users across the fediverse. Furthermore, this is part of Mastodon's database design from its very beginnings.
 
 As a result, Mastodon requires that each ActivityPub actor uniquely maps back to an `acct:` URI that can be resolved via WebFinger.
 
-More information and examples are available at: https://docs.joinmastodon.org/spec/webfinger/
+- [WebFinger information and examples](https://docs.joinmastodon.org/spec/webfinger/)
 
 #### HTTP Signatures
 
@@ -21,11 +37,13 @@ In order to authenticate activities, Mastodon relies on HTTP Signatures, signing
 
 Mastodon requires all `POST` requests to be signed, and MAY require `GET` requests to be signed, depending on the configuration of the Mastodon server.
 
-More information on HTTP Signatures, as well as examples, can be found here: https://docs.joinmastodon.org/spec/security/#http
+- [HTTP Signatures information and examples](https://docs.joinmastodon.org/spec/security/#http)
 
 ### Optional extensions
 
-- Linked-Data Signatures: https://docs.joinmastodon.org/spec/security/#ld
+- [Linked-Data Signatures](https://docs.joinmastodon.org/spec/security/#ld)
-- Bearcaps: https://docs.joinmastodon.org/spec/bearcaps/
+- [Bearcaps](https://docs.joinmastodon.org/spec/bearcaps/)
-- Followers collection synchronization: https://codeberg.org/fediverse/fep/src/branch/main/fep/8fcf/fep-8fcf.md
+
-- Search indexing consent for actors: https://codeberg.org/fediverse/fep/src/branch/main/fep/5feb/fep-5feb.md
+### Additional documentation
+
+- [Mastodon documentation](https://docs.joinmastodon.org/)