api docs: Add changes for community_topic_editing_limit_seconds.
api docs: Add changes for community_topic_editing_limit_seconds.

The previous commit fixed this in the changelog, but it should have
also been documented directly as well.

rht/zulip,zulip/zulip,punchagan/zulip,rht/zulip,eeshangarg/zulip,kou/zulip,eeshangarg/zulip,rht/zulip,andersk/zulip,punchagan/zulip,kou/zulip,showell/zulip,kou/zulip,hackerkid/zulip,kou/zulip,showell/zulip,zulip/zulip,hackerkid/zulip,showell/zulip,showell/zulip,zulip/zulip,kou/zulip,hackerkid/zulip,rht/zulip,hackerkid/zulip,andersk/zulip,punchagan/zulip,zulip/zulip,showell/zulip,zulip/zulip,andersk/zulip,kou/zulip,andersk/zulip,rht/zulip,hackerkid/zulip,hackerkid/zulip,rht/zulip,punchagan/zulip,kou/zulip,zulip/zulip,eeshangarg/zulip,zulip/zulip,eeshangarg/zulip,showell/zulip,punchagan/zulip,andersk/zulip,eeshangarg/zulip,punchagan/zulip,hackerkid/zulip,andersk/zulip,showell/zulip,rht/zulip,punchagan/zulip,eeshangarg/zulip,eeshangarg/zulip,andersk/zulip