Adding implementation information for FIRM (#505)

Co-authored-by: Steve Bate <svc-github@stevebate.net>
Reviewed-on: https://codeberg.org/fediverse/fep/pulls/505
Co-authored-by: Steve Bate <steve-bate@noreply.codeberg.org>
Co-committed-by: Steve Bate <steve-bate@noreply.codeberg.org>

fep/67ff/fep-67ff.md

@@ -76,6 +76,7 @@ The `FEDERATION.md` file can have arbitrary structure and content. The only requ
 - [Iceshrimp.NET](https://iceshrimp.dev/iceshrimp/Iceshrimp.NET/src/branch/dev/FEDERATION.md)
 - [Forte](https://codeberg.org/fortified/forte/src/branch/dev/FEDERATION.md)
 - [NeoDB](https://github.com/neodb-social/neodb/blob/main/FEDERATION.md)
+- [FIRM](https://github.com/steve-bate/firm/blob/main/FEDERATION.md)
 
 ## References
 

fep/d556/fep-d556.md

@@ -245,6 +245,12 @@ Although the definition isn't clear, the "Application Actor" in [FEP-2677] appea
 - Brad Fitzpatrick, [WebFinger], 2013
 - WebFinger\.net [Link Relations][WebFingerRels]
 
+## Implementations
+
+Known implementations include:
+
+* FIRM
+
 ## Copyright
 
 CC0 1.0 Universal (CC0 1.0) Public Domain Dedication

fep/f1d5/fep-f1d5.md

@@ -111,6 +111,7 @@ This list is not comprehensive:
 * Socialhome
 * epicyon
 * apcore
+* FIRM
 
 ### Clients