ERC doc fixes for Emacs 29

[J.P.]

Hi people (Amin, Emacs maintainers, all),

Pardon the intrusion. I know these are busy times.

I was hoping it'd be possible to move a lengthy passage in the ERC
manual, namely, the main auth-source description [1], to its own
subsection in the Integrations chapter. It currently resides in the
Password section of the sprawling Advanced Connecting chapter but feels
rather out of place if not stifling (which, of course, is my own doing).
Basically, it covers all things auth-source in ERC rather than just what
pertains to the entry-point `:password' parameter, and I'm worried users
mainly wanting a quick overview of the latter will groan upon seeing it.

The second patch (also docs-only) just fixes a mistake in a recently
added usage example. Both are low priority but substantive enough (IMO)
to qualify per this admonition from CONTRIBUTE:

  However, this rule is limited to fixing real problems in the
  documentation; cleanups and stylistic changes are excluded.

Of course, should anyone find themselves disagreeing, please say so, and
I will abstain. Otherwise, please expect me to add something closely
resembling these two changes in the next day or so.

Thanks,
J.P.


[1] introduced by this commit (to Emacs 29):

    commit 85c2f3bc3efd9cdd092a6d4fadca5cc04642a2a5
    Author:     F. Jason Park <jp@neverwas.me>
    AuthorDate: Fri Jun 18 04:25:44 2021 -0700
    CommitDate: Thu Jun 30 15:19:53 2022 -0700

    Update ERC's Info doc with network-ID related changes

0001-Add-dedicated-auth-source-section-in-ERC-manual.patch
Description: Text Data

0001-doc-misc-erc.texi-Fix-SASL-typo-and-example.patch
Description: Text Data