Update github.io documentation version list and default

[David Kline (david-c-kline)]

This change adds 2.5.0 to the collection of documentation versions and sets the default to the latest (2.5.0).

Do NOT merge this until the final release process is complete.

[Kurtis (keveleigh)]

I think (Bernadette Thalhammer (@thalbern) Will (@wiwei) correct me if I'm wrong) with the recent docs root changes, this change needs to go into the release branch, since that's where the root layout is loaded from now (hence the fact that prerelease/2.5 is in the list your editing but isn't displayed on the actual docs site).

[David Kline (david-c-kline)]

it will go in when we merge back into mrtk_development.... though I am more than happy to retarget if that is the correct option

[Will (wiwei)]

I think (Bernadette Thalhammer (@thalbern) Will (@wiwei) correct me if I'm wrong) with the recent docs root changes, this change needs to go into the release branch, since that's where the root layout is loaded from now (hence the fact that prerelease/2.5 is in the list your editing but isn't displayed on the actual docs site).

Yep, this is correct - this has to go into prerelease (which then goes to release). There's another pipeline change which we have listed in our release steps which also needs to happen after prerelease-> release/2.5.0, but it's pretty straightforward (i.e. a string change)