Php cheat sheet (#6286)

* Add PHP cheat sheet

* Remove auto indention

* Remove auto indention

* Update alphabet sorting

* Update

Co-authored-by: ImVector <59611597+LuigiImVector@users.noreply.github.com>

* Update more/free-programming-cheatsheets.md

Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

Co-authored-by: ImVector <59611597+LuigiImVector@users.noreply.github.com>
Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

more/free-programming-cheatsheets.md

@@ -24,6 +24,7 @@
 * [MATLAB](#matlab)
 * [MongoDB](#mongodb)
 * [Perl](#perl)
+* [PHP](#php)
 * [Python](#python)
 * [R](#r)
 * [Raspberry Pi](#raspberry-pi)
@@ -186,6 +187,11 @@
 * [PyTorch Official Cheat Sheet](https://pytorch.org/tutorials/beginner/ptcheat.html) - PyTorch (HTML)
 
 
+### PHP
+
+* [PHP Cheat Sheet](https://websitesetup.org/php-cheat-sheet/) - Nick Schäferhoff, WebsiteSetup (HTML, [PDF](https://websitesetup.org/wp-content/uploads/2020/09/PHP-Cheat-Sheet.pdf))
+
+
 ### Python
 
 * [Comprehensive Python Cheat Sheet for Beginners](https://medium.com/the-codehub/comprehensive-python-cheat-sheet-for-beginners-5d76bb038fa2) - Rishi Sidhu, Medium (HTML)