Documentation suggestion: Mention async-bytecomp-package-mode in the installation section of the manual

[Gustavo Barros]

Hi All,

I've seen time and again folks get bitten by trying to install Org with 
`package.el' while having Org loaded.  The latest, but certainly not the 
first and not the last: 
https://www.reddit.com/r/orgmode/comments/jicj1k/how_to_use_org_version_from_orgpluscontrib/

This is well known, and indeed the manual states "important" in bold to 
say that "You need to do this in a session where no ‘.org’ file has been 
visited, i.e., where no Org built-in function have been loaded."

But it is not always easy to ensure that, even when you know what you 
are doing.  And certainly not trivial to users less acquainted with the 
package system and how library loading works, etc.

However, there is a very easy way to ensure that 
installation/byte-compilation is done in a clean environment in package 
`async', namely `async-bytecomp-package-mode'.  From my experience, I 
have a simple:

   (use-package async-bytecomp
     :ensure async
     :defer t
     :custom
     (async-bytecomp-allowed-packages 'all)
     (async-bytecomp-package-mode t))

in my init file.  My `initial-major-mode' is `org-mode' and I've never 
had an installation problem, even though I update `org-plus-contrib' 
carelessly at will on a live session.

`async' is by John Wiegley, and available both at ELPA and MELPA.

Wouldn't it be worth mentioning it in the manual and/or in the 
site/Worg?

Best regards,
Gustavo.