add message about PECL deprecated by PIE

[remicollet]

Additional message when invoked as

• pecl help
• pecl help install
• pecl help upgrade

pear and other commands have not changed (download and upgrade-all may be candidates)

[remicollet]

@asgrim may be of interest for you ;)

[asgrim]

Thanks - you beat me to it, this was in my backlog 🎉 😁

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[remicollet]

In second commit, I add download and upgrade-all and remove message for PHP < 8.1 (which is the minimal version supported by PIE)

[asgrim]

In second commit, I add download and upgrade-all and remove message for PHP < 8.1 (which is the minimal version supported by PIE)

For information only at this time, we are experimentally providing a statically compiled version of PIE which means it could work with any version of PHP (since the PHP running PIE is self-contained in the binary), so this caveat about <8.1 may not be necessary in future (although; it is not compiled for all architectures at the moment)