Add links to useful developer resources to README or wiki

[deleted-user-1]

The extension was built using (a now outdated version of) https://github.com/phpbb-extensions/phpbb-ext-skeleton. It's an official starterkit to bootstrap phpbb extensions.

Documentation about extension development can be found at https://area51.phpbb.com/docs/dev/3.2.x/extensions/index.html (note that this is for 3.2).

phpbb's API can be browsed at https://area51.phpbb.com/docs/code/3.2.x/index.html

Sometimes it's interesting to look how other extensions have solved a certain problem, these are all listed at https://www.phpbb.com/customise/db/extensions-36?sk=d.

XAMPP is one of many available tools to set up a development apache and mysql server and comes with phpmyadmin to inspect databases. https://www.apachefriends.org/faq_linux.html