gopls/doc: update vscode-go GitHub link
gopls/doc: update vscode-go GitHub link

The GitHub repository for vscode-go has been moved to https://github.com/golang/vscode-go. This change reflects that.

Change-Id: I3915ee0db39f8c069c83572893bae2f3d48a4aa9
GitHub-Last-Rev: 8eda352810368352320b7a25846ccbf4d2591c0c
GitHub-Pull-Request: golang/tools#234
Reviewed-on: https://go-review.googlesource.com/c/tools/+/237657
Reviewed-by: Hyang-Ah Hana Kim <d7e82c3c07f92613bcbf9a1e88f6b96c13caa3b0@gmail.com>

golang/tools,golang/tools,golang/tools,golang/tools,golang/tools