Small fixes

[PippaClarkGDS]

Why

Includes 2 small fixes for the tech docs - browser information and removal of mention of private beta.

What

n/a

Technical writer support

has previously been through review.

How to review

n/a

Changelog

n/a

Confirm

• [x] I have checked if any docs change here also requires updates to other repositories (ADRs / RFCs, README.md, Team Manual, elsewhere in these docs)
• [x] Where there is any overlap I have updated or opened a PR for corresponding changes