Update info re accessibility training

[sarawilcox]

Request from CDDO:

It appears that https://service-manual.nhs.uk/accessibility/getting-started needs an update. GDS / CDDO no longer run accessibility training courses across government and the public sector, so could you please remove that section of the page.

Other information about the accessibility community is still valid, although it isn't specifically a GOV.UK community, it is a cross public sector community, managed by CDDO.

Agreed to make updates.

We may be able to post some different info about accessibility training sessions. For example, that NHSE runs lunchtime sessions (assuming any staff can attend them) and other organisations may run sessions internally or be able to bring in an accessibility agency to run a session.

[sarawilcox]

Draft content in https://github.com/nhsuk/nhsuk-service-manual/tree/mixed-bug-fixes-for-feb-releases. Waiting for feedback from Max.