help_docs: Update `rename-a-stream` help doc.
help_docs: Update `rename-a-stream` help doc.

Uses new `select-stream-view-general.md` for instructions.

Also, updates text for locating the button/icon and uses
the `save-changes.md` to correct the final instruction/step.

andersk/zulip,andersk/zulip,zulip/zulip,zulip/zulip,kou/zulip,kou/zulip,kou/zulip,rht/zulip,kou/zulip,rht/zulip,zulip/zulip,andersk/zulip,zulip/zulip,rht/zulip,andersk/zulip,kou/zulip,zulip/zulip,zulip/zulip,andersk/zulip,kou/zulip,rht/zulip,rht/zulip,zulip/zulip,rht/zulip,andersk/zulip,andersk/zulip,kou/zulip,rht/zulip