Contribution page on the guidance site

[GCHQ-Developer-465]

Summary

A page on the site where all the instructions are in one place.

💬 Description

Going through all the contribution information we have on the site:

• Community Contribution
• Contribution Criteria

See what is valuable and needed.

The pages need to condensed into one page that has all the instructions on how to contribute.

Furthermore, users are having to read 2+ .md files. This needs to be improved so that there is a flow form beginning to end on contributing to the ICDS.

Key features to include:

• Rebasing
• Scoping
• Timings

[ad9242]

would be good to resolve this as part of the work: https://github.com/mi6/ic-ui-kit/issues/1724