Add Bluesky topnav feature; and update name of X (formerly Twitter)

[PhilReedData]

From issues #321, copying the Twitter topnav code to include Bluesky as another choice. Uses the Font Awesome logo again. Docs page also updated.

Tested in FAIRDOM website FAIRdom/fairdom.github.io#131


Here it uses my remote fork https://github.com/PhilReedData/elixir-toolkit-theme/releases/tag/bluesky-002 and shows both Twitter and Bluesky.

I updated the name of Twitter to 'X (formerly Twitter)' which I have seen on many sites, though they tend to be dropping the word 'Twitter' now too. It looks a little odd, showing an X logo then just an X text, if we were to drop the 'formerly Twitter' bit too, though I think that's on Elon Musk to blame. I don't mind if you drop this part of my PR and just add Bluesky.

[bedroesb]

@PhilReedData I think your somebody was first to add this #324 . I am not a fan of the formerly twitter thing and I am thinking of dropping the text all together, see the other linked PR.

Do you think we can work further on it in the other PR and I close this one?

[PhilReedData]

Sure, yes close this PR, perhaps use my documentation edit to inspire work in that one.

[bedroesb]

@PhilReedData Like always, I am thankful for your contributions. Hope the linked PR in the issue will not go unnoticed next time :) Have a nice weekend.

[anenadic]

@PhilReedData I think your somebody was first to add this #324 . I am not a fan of the formerly twitter thing and I am thinking of dropping the text all together, see the other linked PR.

That was me 😆 @PhilReedData - I independently noticed the same issue and came to fix it as we needed it for RSQKit too.