Provide list of public matrix servers in Riot register new user form

[MurzNN]

At now Riot provides only one default server for register new account (matrix.org, or other, predefened in config.json).

Will be good to provide dropdown list of public matrix servers (that can be altered via config.json) for user select. Example of public matrix servers list is here https://www.hello-matrix.net/public_servers.php

This will easily show for users that [matrix] is not centralized, but federated network and user can select the server to register.

Also near this server selection dropdown will be good to place a link "How to install own [matrix] server?".

[lampholder]

There are two parts to this:

• adding the feature to riot generally
• enabling the feature on https://riot.im specifically

I think it's a reasonable feature to add (though I expect the common case of individuals/groups running their own riot instance is that it is most closely associated with a single matrix homeserver).

Adding it to https://riot.im is more tricky, since we'd have to do some additional UX to let new users know that these servers are outside of 'our' span of control (i.e. the people who commit to keeping https://riot.im up and running cannot commit to keeping https://matrix.otherhomeserver.com available).

[benparsons]

Mutliple customers have requested the ability to pass a list of homeservers to their element-web instance.

[hex-m]

Related Issue: Support for multiple default homeservers