Streamline where the changelog is published

[mikenikles]

There are currently two places where product updates are communicated:

• https://www.gitpod.io/docs/release-notes/
• https://www.gitpod.io/docs/changelog/

A common standard is to use /changelog at the root of the domain. To accomplish this, the following tasks are required:

• Create a new /changelog page
• Migrate the content from /docs/release-notes
• Migrate the content from /docs/changelog
• Remove the /docs/release-notes and /docs/changelog pages
• Configure redirects from /docs/release-notes and /docs/changelog to /changelog

[mikenikles]

While the above is still the end goal, the following steps are minimal viable changes to start promoting the /changelog URL asap:

• Redirect /changelog to /docs/changelog
• Update /docs/changelog when a new release is available