Add support for multiple categories in exported requirements

[dojutsu-user]

Closes: #5397

This adds a category option to the requirements command. If specified a category, it will only generate the requirements of that category.

[oz123]

Awesome work! Can you add a news snippet?
Then we are ready to merge.

[dojutsu-user]

Thank you @oz123 😄,

Can you add a news snippet?

I am not sure what is news snippet. Can you help me here.

[oz123]

We use a tool called town crier to update the changelog for the releases .
If you check the directory news you'll see what are these snippets.
Every time the release is created the are removed, so you can also look at the history of this directory.
Hope this helps. Thanks again for your contribution!

[dojutsu-user]

Thanks @oz123,
I have added news. Let me know if that requires some changes.

[dojutsu-user]

Thanks For Merging @oz123.
Can you also add hacktoberfest-accepted label in the PR.