docs: workaround to use PHP in Composer scripts (#610)
* add @php workaround to known-issues.md
* minor tweaks
* switch to sh
Co-authored-by: Kévin Dunglas <kevin@dunglas.fr>
* Update known-issues.md: sh compat
* change language name
---------
Co-authored-by: Kévin Dunglas <kevin@dunglas.fr>
