Doc: move existing links from 'silx.org' to 'readthedocs'

[payno]

Closes #4304

PR summary

This PR is linked to moving documentation officialy to readthedocs. It update a set of link from silx.org

AI Disclosure

• No AI used
• AI tool(s) ... used for ...

Operation done at edna-site (helped by AI :( ):

• added a .htaccess at ../doc/silx/latest to do the redirection

# Redirect silx.org/doc/silx/latest/ to silx.readthedocs.io/en/stable
RewriteEngine On

RewriteRule ^(.*)$ https://silx.readthedocs.io/en/stable/$1 [R=301,L]

• Added a specific configuration for silx to allow redirection for both http and https

<VirtualHost *:443>
    ...
    DocumentRoot /var/www/silx

    ...
    <Directory /var/www/silx/doc/silx/latest>
        Options Indexes FollowSymLinks
        AllowOverride FileInfo
        Require all granted
    </Directory>

    SSLEngine on

    ...
</VirtualHost>

And then we need to restart apache2 sudo systemctl restart apache2

✔️ Checked that other docs are not modified by this modification

[loichuder]

Suggested change

	- `Documentation on silx.org <https://silx.readthedocs.io/en/latest/>`_
	- `Documentation on Read The Docs <https://silx.readthedocs.io/en/latest/>`_

[loichuder]

Personally, I would remove these. I feel it does not add much.