Merge branch 'matrix' into 'master'

Since mid-April 2021, many `#tor-*` channels are bridged (or

"[plumbed](https://matrix.org/bridges/)") between the [OFTC IRC network](https://oftc.net) and the

[Matrix.org](https://matrix.org/) home server. This is still somewhat of an experimental

status, but so far it seems to be working well.

status, but so far it seems to be working well. These channel are listed in

[#tor-space](https://matrix.to/#/#tor-space:matrix.org).

By default, you will appear on IRC as a user like "YourMatrixName\[m\]".

You can override this by sending `!nick <yournick>` to "OFTC IRC Bridge

status". If your nick is registered, you will get a PM from NickServ stating

You can override this by sending `!nick <yournick>` to

[@oftc-irc:matrix.org](https://matrix.to/#/@oftc-irc:matrix.org).

If your nick is registered, you will get a PM from

[NickServ](https://matrix.to/#/@_oftc_NickServ:matrix.org) stating

that you need to authenticate. Do so by responding with `identify

\<yourpassword\>`.

\<yourpassword\>`. If your nick isn't registered, you should consider doing so.

You can do it by sending `register <password> <e-mail>` to

[NickServ](https://matrix.to/#/@_oftc_NickServ:matrix.org), and following

the instructions.

Also note that you can join *any* channel on bridged IRC networks (Freenode and

OFTC) through the [Portal rooms](https://matrix.org/bridges/) functionality.

For example, `#freenode_#channelname:matrix.org` corresponds to `#channelname`

on Freenode. This is the only supported way to access Tor's internal channels

through Matrix (you will need to set your nick first; see above). To join a portal room, send

`!join #channel \<channel password\>` to "OFTC IRC Bridge status".

For example, `#_oftc_#channelname:matrix.org` corresponds to `#channelname`

on OFTC. This is the only supported way to access Tor's internal channels

through Matrix (you will need to register and identify your nick first; see

above). To join a portal room, send `!join #channel \<channel password\>` to

@oftc-irc:matrix.org. You may get kicked of internal channels seemingly at

random when the bridge restart. You'll then have to re-authenticate to NickServ,

and send a `!join` command again.

For more information see the general [Matrix bridge

documentation](https://matrix.org/bridges/) and the [IRC bridge