DOP-5251: update projects route to include offline download url

[seungpark]

Ticket

DOP-5251

Notes

• This route already exists on prod to get all the projects and corresponding branches https://snooty-data-api.mongodb.com/projects - Adding onto this route so this also returns the offline download URL for this each page. Currently in pool.repos_branches there is a test property under 'cloud-docs - master' branch for offlineUrl (generated by Netlify extension).
• The proposal is that the front end will use this route to populate the modal for users to see available downloads
• Since staging is Okta auth'ed, testing in staging / docs-qa will require an additional step, as you need to be okta-verified to make requests to the server

README updates

• • This PR introduces changes that should be reflected in the README, and I have made those updates.
• • This PR does not introduce changes that should be reflected in the README

[seungpark]

this change was to mitigate this error for failed dependencies

[rayangler]

(Nit) Can we change the PR title to include context?

[seungpark]

(Nit) Can we change the PR title to include context?

thanks for pointing that out! done