Update links to direct users to https://idm.wikimedia.org/ instead of Wikitech links

Note to self: instructions at https://wikitech.wikimedia.org/wiki/Help:Toolforge/My_first_Pywikibot_tool#Accessing_Toolforge_for_the_first_time are nice and should be compared to what is in the quickstart. The note about not prefixing your toolname with 'tools.' and about access delays seem like good things to warn about, and I don't think I've encountered them elsewhere in the docs.

Account setup content in this doc was also cleaned up via work on T346384.

Looks good! The account creation flow is complex, but you've done a good job making it clear what users need to do. I made a few small edits and took a few notes (noting that some of the comments relate to portions of the doc outside the scope of your changes):

• This section includes the become command, but it isn't explained until a later section. Since this step is about the change in the prompt, can the code sample in step 3 be reduced to just username@tools-sgebastion-10:~$?
• I think it would be better to remove the reference to dev.toolforge.org (and maybe also the introduction of "bastion" as a term) since quickstart users are unlikely to be doing heavy processing.
• In $ ssh -i <path-to-ssh-private-key> username@login.toolforge.org, there's inconsistent formatting to represent placeholders (with and without angle brackets).
• This section has unnumbered steps whereas the other sections have numbered steps.