Add Keywords To OPENKEYWORDS.md

[aditya1rawat]

We are always in need of defining more keywords & operators to convert to hacklang. Let us know if we are missing any in our OPENKEYWORDS.md and make sure to check if they are already taken in README.md

Then Fill Out The Application Here: https://airtable.com/shr69zRPjSpmrLdmh

[jbis9051]

See develop branch

[aditya1rawat]

This should always stay open. People can see this when they come to the repo and can "apply" for keywords