importing-postgres.md: Add 'Troubleshooting' w/workaround for ownership

If a Postgres dump contains ALTER TABLE ... OWNER_TO <username>
statements which set the owner to a username different from
'synapse' the post Postgres import task will fail complaining
about lack of role.

Changing the matrix_postgres_connection_username group var has no
effect. However, the ALTER TABLE statements (and accompanying comments)
can be rewritten to change the username to 'synapse', which permits the
import task to succeed.

From a sample of 1, having the owner set in this was causes no
discernable side effects on the homeserver.

One could also remove the two variables from the docs completely,
because they are set by the playbook automatically.

Error: javax.net.ssl.SSLPeerUnverifiedException: Certificate for
<matrix.<your-domain>> doesn't match any of the subject alternative
names: [<your-domain>]

Fixes #577 (Github Issue).

Fixes #579 (Github Issue).

Fixes #573 (Github Issue).

Fixed repository link for mx-puppet-steam

- https://github.com/icewind1991/mx-puppet-steam is the link that's referenced by the documentation.
- The previous link, https://github.com/matrix-steam/mx-puppet-steam, is invalid/inaccessible to the public.

Fixed Steam link

Run all API self checks in check_mode

swap links

Expose reCAPTCHA variables and document

Related to #554 (Github Pull Request).

Related to #557 (Github Pull Request).

Add mx-puppet-steam

Upgrade Synapse (1.15.1 -> 1.15.2)

Related to #540 (Github Pull Request).

Add mx-puppet-discord

https://github.com/matrix-discord/mx-puppet-discord/issues/80

Thanks Sorunome for setting up the automated build

Related to #551 and #555 (Github Pull Requests).

Add mx-puppet-twitter

Add mx-puppet-instagram

4.5.1.3 fixes a security vulnerability:
https://github.com/coturn/coturn/security/advisories/GHSA-c8r8-8vp5-6gcm