docs: add stdlib.md
Updates golang/go#38603
Change-Id: Ie67fb8456178cbcbbbe18fd38c6b74f83c84222b
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/249057
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
diff --git a/docs/stdlib.md b/docs/stdlib.md
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+++ b/docs/stdlib.md
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+# Standard library development
+
+vscode-go and gopls can be used for developing the standard library, but require configuration.
+
+First, you **must open the `src/` folder in VS Code**, not the Go tree root.
+(See [golang/go#32394](https://github.com/golang/go/issues/32394).)
+
+Then, you need to configure the workspace, by placing the following in `src/.vscode/settings.json`.
+
+```json5
+{
+ // Use the local go tool. This needs to be built with make.bash.
+ "go.alternateTools": {
+ "go": "~/godev/bin/go"
+ },
+ // Build a separate set of tools. For golang/vscode-go#294.
+ "go.toolsGopath": "~/.vscode/godev",
+ // Don't reformat HTML files since we have a custom style.
+ "html.format.enable": false,
+}
+```
+
+The above assumes the Go tree is checked out at `~/godev`. If your Go tree is somewhere else, modify
+`go.alternateTools.go` accordingly.
+
+You can add `.vscode` to `.git/info/exclude` to avoid risking checking `settings.json` into git.
+
+If you see an "inconsistent vendoring" error, please report it at
+[golang/go#40250](https://github.com/golang/go/issues/40250).
+
+See also [golang/go#38603](https://github.com/golang/go/issues/38603).
