CIVICRM-1707 Remove incorrect statement about open_basedir being deprecated. Safe mode was deprecated in PHP 5.3, so no longer relevant. Include minimum PHP configuration recommendations and links.

Update Requirements doc to mention that PHP7.4 is supported from MySQL 5.37 and...

See merge request documentation/docs/installation!27

Update Requirements doc to mention that PHP7.4 is supported from MySQL 5.7 and also to clarify that all CMSes now supoort MySQL8 and add a note about installing on Cloud Service Providers such as AWS and Azure

Make D9 support visible

See merge request documentation/docs/installation!26

This option was often set permissively in D8 project-templates - and it's
often set restrictively in D9 project-templates.

Adding the step generally shouldn't change anything for D8 admins -- and for
D9 admins it enables installation to proceed.

* This is predictably getting out of sync 'docs/drupal8'
* 'docs/drupal8' is getting updates to reference both 8+9

Update requirements.md  based on https://civicrm.org/blog/dev-team/civicrm-534-release

See merge request documentation/docs/installation!25

Move the multisite installation from the SysAdmin guide

See merge request documentation/docs/installation!22

Timestamp mismatch warnings link to this doc - make it more useful.

See merge request documentation/docs/installation!23

Add historical PHP & MySQL compatibility info

See merge request documentation/docs/installation!24

Remove the section on clean URLs in WordPress

Closes #7

See merge request !20

This is being migrated to the SysAdmin guide as it is no longer required
for new installations

Docs for how to use unicode fonts for pdf output

See merge request !19

Change some broken absolute links to relative links

See merge request !18

documentation/docs/sysadmin#3 - Rework "Get the code" and "Run the installer"

See merge request documentation/docs/installation!15

General themes/changes:

* Rewrite as a standalone page. This was previously content in the D8 page.
* Include the `curl ... cv.phar ...` command.
* Move discussion of the `core:install` options and common problems into collapsed admonitions.
* The "next level" docs for `cv core:install` are in the Dev Guide. Add links.
* Add a section for "Configure the site".
* Add a "Limitations" section.

* Use simpler language
* For optional commands, link to relevants docs.