This is a very basic tutorial on how to use patterns in my Obsidian paste formatter plugin. The patterns are default Javascript regexes, so for for more help, you can also google "javascript regex tutorial".
Let's take this pattern as an example:
https://github.com/.+?/.+?/issues/([0-9]+)
This pattern matches links to GitHub issues, for example:
https://github.com/sjorso/obsidian-paste-formatter/issues/195