Document php extra php fpm.conf

[Gofannon]

Problem

• Issue while packaging php application
• trouble to understand differents "usage" of the helper https://github.com/YunoHost/yunohost/blob/ec271043cdcf28ba74acc87d4ae854d8c2852695/helpers/php#L59 and when it generates a "full php config" or when it uses the one provided in the "conf folder"

Solution

Proposal to enhance the example from my understand on php management

1. ynh_add_fpm_config : add "extra_php-fpm.conf" to be added at the end of the "php generation config" to customize it
2. harmonize "ynh_add_fpm_config" by using "fpm_footprint" variables => should be used in template mode
3. small comments

Some TODO are still the code to discuss

I took example on the grav and nextcloud package while working on dokuwiki

PR Status

• [x] Code finished and ready to be reviewed/tested
• [ ] The fix/enhancement were manually tested (if applicable)

Automatic tests

Automatic tests can be triggered on https://ci-apps-dev.yunohost.org/ after creating the PR, by commenting "!testme", "!gogogadgetoci" or "By the power of systemd, I invoke The Great App CI to test this Pull Request!". (N.B. : for this to work you need to be a member of the Yunohost-Apps organization)

[Gofannon]

can be reviewed

[ericgaspar]

closing in favor of #210