Update Additional Features draft doc, include version features

[dagood]

• add Microsoft Build of Go - Additional Features document #1899
• go version should inform that the go binary is generated by microsoft  #262
• [release-branch.go1.26] Update release notes for 1.26 #2078 can condense a lot with a ref to this doc.

Simplify, focus on features without exhaustively explaining enable/disable, and fill out the list. Include a specific note about security (regarding our crypto changes) to have another chance to clear up any misunderstanding about that.

[qmuntal]

Also, add a TODO section for the TLS settings aligned with MS policies. That is orthogonal to the system-provided crypto. I'll fill it in a follow-up PR.

[dagood]

I added some content for the TLS alignment feature based on the patch's godebug doc, could still probably use filling in (potentially a ref to more details in FIPS doc).

[qmuntal]

LGTM++!

[karianna]

Maybe not for this round but something kept bugging me and then I realised what it was. Should we consider having the versions tabbed, or in a dropdown like I see on other major public fdocs pages for build tools like Gradle or versions of Java? I might be very wrong abotu the Ux of that given what you're trying to convey here sometimes but thought I'd mention it,

[gdams]

LGTM, I agree with Martijn that we might be able to present this information in a better way but I like to move fast and iterate with docs

[dagood]

Should we consider having the versions tabbed, or in a dropdown like I see on other major public fdocs pages for build tools like Gradle or versions of Java?

Unfortunately, we don't have these kinds of tools in Markdown, the best we have is <details><summary>…</summary>…</details> which isn't all that ergonomic. But: what I expect is that when a version goes EOL, we remove references to that version in docs like this to keep it readable.

An idea @gdams brought up offline (or something similar that led to this? 😄) is to maybe get this info accessible via go doc so you can easily tell what your specific version will do without cross-referencing these docs vs. your version. (An obstacle for that is that it's annoying to acquire the Microsoft build of Go on a dev machine, which #146 (dl) would help with.)