Created docusaurus-spin template repository to Spin Up Hub

[VamshiReddy02]

This PR adds the spin-docusaurus template repository to the Spin Up Hub. I'm sorry for closing my Last PR because of some technical issues. All the requested changes have been made. please let me know if there are any further changes to be made.

Fixes issues: #801

Pre-Merge Content Checklist

This documentation has been checked to ensure that:

• The title, template, and date` are all set
• Does this PR have a new menu item (anywhere in templates/*.hbs files) that points to a document .md that is set to publish in the future? If so please only publish the .md and .hbs changes in real-time (otherwise there will be a menu item pointing to a .md file that does not exist)
• File does not use CRLF, but uses plain LF (hint: use cat -ve <filename> | grep '^M' | wc -l and expect 0 as a result)
• Has passed bart check

✅ content/api/hub/template_docusaurus.md

• Has been manually tested by running in Spin/Bartholomew (hint: use PREVIEW_MODE=1 and run npm run styles to update styling)

• Headings are using Title Case
• Code blocks have the programming language set to properly highlight syntax and the proper copy directive
• Have tested with npm run test and resolved all errors
• Relates to an existing (potentially outdated) blog article? If so please add URL in blog to point to this content.

[VamshiReddy02]

@tpmccallum please review this PR, and let me know if there are any additional modifications required.

[tpmccallum]

LGTM @VamshiReddy02
Thanks for the contribution.
Champion!!!