Fix #1822 - support go-langserver lsp.

doc/ale-go.txt

@@ -7,7 +7,7 @@ Integration Information
 
 The `gometalinter` linter is disabled by default. ALE enables `gofmt`,
 `golint` and `go vet` by default. It also supports `staticcheck`, `go
-build` and `gosimple`.
+build`,  `gosimple`, and `golangserver`.
 
 To enable `gometalinter`, update |g:ale_linters| as appropriate:
 >
@@ -114,5 +114,25 @@ g:ale_go_staticcheck_lint_package           *g:ale_go_staticcheck_lint_package*
   current file.
 
 
+===============================================================================
+golangserver                                              *ale-go-golangserver*
+
+g:ale_go_langserver_executable                 *g:ale_go_langserver_executable*
+                                               *b:ale_go_langserver_executable*
+  Type: |String|
+  Default: `'go-langserver'`
+
+  Location of the go-langserver binary file.
+
+g:ale_go_langserver_options                       *g:ale_go_langserver_options*
+                                                  *b:ale_go_langserver_options*
+  Type: |String|
+  Default: `''`
+
+  Additional options passed to the go-langserver command. Note that the
+  `-gocodecompletion` option is ignored because it is handled automatically
+  by the |g:ale_completion_enabled| variable.
+
+
 ===============================================================================
   vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl: