various minor edits

proposals/1772-groups-as-rooms.md

@@ -108,7 +108,9 @@ would be needed to distinguish from a deleted state event. Something like:
 
 Name, Topic, Membership etc share the same events as a normal room.
 
-The flair image for a group is given by the room avatar.
+The flair image for a group is given by the room avatar. (In future it might
+preferable to use hand-crafted small resolution images: see
+[matrix-doc#1778](https://github.com/matrix-org/matrix-doc/issues/1778).
 
 Long description requires a new event: `m.room.description`.  This can also be
 used for rooms as well as groups.
@@ -191,12 +193,12 @@ Of these, option 3 feels best?
 
 ## Dependencies
 
-This needs peeking to work effectively on CS API.
-([MSC1776](https://github.com/matrix-org/matrix-doc/issues/1776))
+This needs peeking to work effectively over the CS API
+([MSC1776](https://github.com/matrix-org/matrix-doc/issues/1776)).
 
 This needs peeking to work effectively over federation (e.g. by having servers
-join remote rooms as @null:example.com in order to participate in them for
-peeking purposes) - ([MSC1777](https://github.com/matrix-org/matrix-doc/issues/1777))
+join remote rooms as `@null:example.com` in order to participate in them for
+peeking purposes - [MSC1777](https://github.com/matrix-org/matrix-doc/issues/1777)).
 
 These dependencies are shared with profiles-as-rooms
 ([MSC1769](https://github.com/matrix-org/matrix-doc/issues/1769)).
@@ -220,13 +222,21 @@ fix for bridged rooms in general too, however.
 This also consciously sacrifices the ability for a group server to provide
 different 'views' of groups to different querying users, as being
 overengineered.  Instead, all common use cases should be modellable by modelling
-group memnbership as room membership (nesting if required).
+group membership as room membership (nesting if required).
 
 ## Issues
 
 How does this work with
 [MSC1228](https://github.com/matrix-org/matrix-doc/issues/1228) (removing MXIDs)?
 
+## Unstable prefix
+
+While this proposal is not in a published version of the specification,
+implementations should use `org.matrix.msc1772` to represent the `m`
+namespace. For example, `m.room.subgroup` becomes
+`org.matrix.msc1772.room.subgroup`.
+
+
 ## History
 
  * This replaces MSC1215: https://docs.google.com/document/d/1ZnAuA_zti-K2-RnheXII1F1-oyVziT4tJffdw1-SHrE