help user find information on configuring emacs

Yesterday I had a problem with the unicode fonts, and I fixed it following the instructions in the Emacs mode README file. (I installed emacs-unicode-fonts.) But to do this I had to (1) remember that Soonho once told us about this, and (2) look for the README. Users with the same problem may be more frustrated.

Two possible solutions:

(1) On leanprover.github.io, add a more prominent link to the Emacs README file, under "Download". For example, at the bottom of the page, we can write:

Once Lean is installed, you can start the Emacs with Lean mode using the command leanemacs. For information on how to configure Emacs yourself and install unicode-friendly fonts, see [here].

(2) On the Documentation page, we can start a FAQ. This could go in a "troubleshooting" section. We could do this, for example, by changing the header "Forum" to "Additional Information", with entries:

o You are welcome to join the [Lean user forum] on Google Groups.
o There is also a list of [Frequently Asked Questions].

@leodemoura @soonhokong ? I will be happy to make either or both of these changes. (I am not sure how to set up a new page for the FAQ, but I can probably figure it out.)

Start by inspecting the Download and Documentation pages on leanprover.github.io, then locate the Emacs mode README referenced in the issue. Confirm whether the prominent Download link, a troubleshooting FAQ, or both fit the existing page structure. Done means users can easily find the Emacs configuration and unicode-font guidance, with working links.