gopls/doc: Add plugin for Lapce to gopls documentation

Add [Lapce](https://lapce.dev) Go plugin to `gopls` documentation

Change-Id: I58ec42d69708b519cfba3de1cdee269ffecdbbc4
GitHub-Last-Rev: 37762df
GitHub-Pull-Request: #413
Reviewed-on: https://go-review.googlesource.com/c/tools/+/448235
Auto-Submit: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

Author: Elara6331

gopls/README.md

@@ -22,6 +22,7 @@ To get started with `gopls`, install an LSP plugin in your editor of choice.
 * [Atom](https://github.com/MordFustang21/ide-gopls)
 * [Sublime Text](doc/subl.md)
 * [Acme](https://github.com/fhs/acme-lsp)
+* [Lapce](https://github.com/lapce-community/lapce-go)
 
 If you use `gopls` with an editor that is not on this list, please send us a CL
 [updating this documentation](doc/contributing.md).