Add missing codehosting doc; fix broken link

[nielsenjared]

This PR refers to canonical/open-documentation-academy#78

It adds the missing "How To Use Codehosting Locally" page and fixes the corresponding link in code.rst. I put this file in the /how-to directory given the nature of its content, but let me know if it belongs elsewhere. Running make linkcheck throws a toctree error. Let me know if this needs to be added to an index.rst.

[jugmac00]

Yes, indeed - we need to add all newly added files to an index. Thank you!

[nielsenjared]

I added codehosting-locally under the "Launchpad development tips" in how-to/index.rst. Let me know if it belongs somewhere else. I'm no longer getting the toctree error, but I'm still getting this:

WARNING: unknown document: 'how-to/codehosting-locally' [ref.doc]

Let me know if I need to do anything to resolve it.

[jugmac00]

Thanks! I won't be able to look into it this week, but I will hope to be able to follow up soon after that.

[alvaro-crespo]

Thanks a lot for the contribution @nielsenjared ! FYI the warning was coming from <../how-to/codehosting-locally>, that was missing the ../ when referencing the code hosting doc.

I'll also add this document inside the 'Launchpad Development Tips' section.