doc/go1.16: document go command changes for Go 1.16

[dmitshur]

As of filing this issue, the Go 1.16 draft release notes contained the following HTML:

<h3 id="go-command">Go command</h3>

<p>
  TODO

  <!-- CL 237697: https://golang.org/cl/237697: cmd/go: error when -c or -i are used with unknown flags -->
  <!-- CL 255052: https://golang.org/cl/255052: cmd/go: default to GO111MODULE=on -->
  <!-- CL 266420: https://golang.org/cl/266420: yes (mention go help vcs): cmd/go: add GOVCS setting to control version control usage -->
  <!-- CL 244773: https://golang.org/cl/244773: cmd/go/internal/modload: drop requirements on excluded versions -->
</p>

And these TODOs:

TODO: write and link to section in golang.org/ref/mod
TODO: write and link to blog post
[...]
TODO: write and link to section in golang.org/ref/mod
TODO: write and link to tutorial or blog post

Per golang.org/s/release, it's a release blocker for Go 1.16 Beta 1 to have a complete draft of the eventual release notes, and so the TODO needs to be resolved.

A sequence of steps to resolve this issue may be:

1. Come up with a draft release note entry in this issue, then move the issue to NeedsFix state.
2. Send a CL with "doc/go1.16:" prefix and include "For doc: write Go 1.16 release notes #40700. Fixes #{this issue}." in the body.

[bcmills]

@jayconrod, is this resolved by https://golang.org/cl/274438?

[jayconrod]

Yes, https://golang.org/cl/274438 removed all the TODOs listed here. I saw Alex's email to gophers, but i didn't see this issue.

@matloob I'll leave this issue open for now. Please close it after adding a note for -overlay.

[dmitshur]

CL 274438 has resolved all user-facing TODOs in the draft 1.16 release notes, so I think the rest of the work on this issue doesn't need to block beta 1.

[jayconrod]

https://golang.org/cl/274438 is merged, so I think we can close this.

[dmitshur]

@jayconrod Has the note for -overlay been added too (as you mentioned in #42893 (comment)), or is it okay not to have an open issue for that? Just want to confirm that it's not missed unintentionally.

[jayconrod]

Oops, I'm sorry, https://go-review.googlesource.com/c/go/+/274714 is the CL adding the -overlay note, and it has not been merged yet, so reopening.

[gopherbot]

Change https://golang.org/cl/274714 mentions this issue: cmd/go: add documentation for the -overlay flag

[dolmen]

Is there some reference documentation about the -overlay flag? The not-yet-published 1.16 release notes which mention -overlay doesn't link to documentation about the JSON file structure with example.

[dmitshur]

@dolmen The -overlay flag is documented in the not-yet-published 1.16 cmd/go documentation, search for "-overlay" on that page.