Fix facts and words

Signed-off-by: Tulir Asokan <tulir@maunium.net>

proposals/2828-restrict-user-ids.md

@@ -1,13 +1,12 @@
 # Proposal to restrict allowed user IDs over federation
-Currently the spec has [an appendice specifying allowed user ID grammar](https://matrix.org/docs/spec/appendices#user-identifiers).
+Currently the spec has [an appendix specifying allowed user ID grammar](https://matrix.org/docs/spec/appendices#user-identifiers).
 The spec makes it seem like user IDs can only consist of printable ASCII
 characters, excluding space and `:`. However, the user ID grammar is not
 actually a part of the event authorization rules, meaning most server
 implementations will accept user IDs with arbitrary unicode characters.
 
-Synapse, Construct and Dendrite will accept arbitrary unicode, while Conduit
-believed the spec appendice and is therefore unable to join rooms with users
-whose user IDs contain characters not allowed by the historical user ID grammar.
+Synapse and Dendrite will accept arbitrary unicode, while Construct and Conduit
+believed the spec appendix.
 
 ## Proposal
 The proposed solution is applying the historical user ID grammar in step 5 of
@@ -23,7 +22,7 @@ the room v1 event authorization rules. A new step is added between 5.a. and 5.b.
 The changes are applied on top of room v6.
 
 ## Note about the user ID grammar spec
-The user ID grammar spec appendice needs to be updated to mention that room
+The user ID grammar spec appendix needs to be updated to mention that room
 versions prior to this new version can contain arbitrary unicode user IDs,
 so clients and servers must be able to handle such users.