This commit fixes the following help pages -
- configure-who-can-create-a-stream.md to use "Stream permissions"
subsection and not "Other permissions".
- configure-who-can-invite-to-streams.md to use "Stream permissions"
subsection and not "Other permissions".
- restrict-wildcard-mentions.md to use "Stream permissions" subsection
and not "Organization permissions".
- restrict-bot-creation.md to use "Other permissions" subsection and
not "Organization permissions".
- restrict-visibility-of-email-addresses.md to use "User identity"
subsection and not "Organization permissions".
This commit moves the wildcard mentions documentation to a top-level page.
Edited by tabbott to deduplicate with the existing docs, and add cross-links.
sahil839