The link above lead to a website with markdown cheatsheet, useful for making good looking md files.
The link above leads to a 7 minute long vim tutorial, which will definitely help you to get out of vim and also some other stuffs.
The link above leads to a geeks for geeks website that will teach you the basics on how to use the sed command
The link above leads to a geeks for geeks website that will teach you the basics on how to use the awk command
The link above will send you to a youtube tutorial which will regex in about 15 minutes