Specify room version 10: knock_restricted and int power levels (#1099)

* Clarification on historical power level handling

* Revert "Clarification on historical power level handling"

This reverts commit f443b3d5a9afac3095b14a72ec471ba06f4cc78b.

* Clean up

* Let us try this again not using VS Code

* Markdown is full of mysteries

* Move stringy power levels to room versions

* Describe range

* Fix minor issues with previous room version stuff

* Copy/paste v9 into v10

* Describe deprecated formatting

* Paste unmodified auth rules from v8 into v10

* Move 9.1 to 9.3, add 9.1 and 9.2 for integer enforcement

* Add knock_restricted to v10 auth

* Misc cleanup and clarification for fragments

* Describe `knock_restricted` client changes

* Changelogs

* spelling

* Apply suggestions from code review

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

* Apply code review suggestions manually

* Fix v9 redactions

* Fix auth rules clarity issues

* Apply suggestions from code review

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

* Remove false integer requirements

Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>
Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

data/event-schemas/schema/m.room.join_rules.yaml

@@ -12,6 +12,10 @@ description: |
   * `restricted` - anyone able to satisfy at least one of the allow conditions is
     able to join the room without prior action. Otherwise, an invite is required.
     Only available in rooms [which support the join rule](/rooms/#feature-matrix).
+  * `knock_restricted` - a user can request an invite using the same functions offered
+    by the `knock` join rule, or can attempt to join having satisfied an allow condition
+    per the `restricted` join rule. Only available in rooms
+    [which support the join rule](/rooms/#feature-matrix).
   * `private` - reserved without implementation. No significant meaning.
 properties:
   content: