[gopls-release-branch.0.6] all: merge master into gopls-release-branch.0.6

fe37c9e1 all: replace all usages of os/exec with golang.org/x/sys/execabs
a46736d9 internal/lsp/source: handle possible nil pointer in rename check
e0d20156 gopls/doc: rewrite troubleshooting.md
d78b04bd gopls/doc: clean up and slightly reorganize documentation
1bdb73f5 gopls/doc: move contents of golang/go#36899 to documentation
f9643685 gopls/internal/regtest: fix synchronization for TestUseGoplsMod
8b4aab62 gopls/doc/vscode.md: update vscode setting example

Change-Id: Iec71457cdff70ef15b77cf4193a0006f5ca47c01
diff --git a/internal/lsp/debug/info.go b/internal/lsp/debug/info.go
index d458019..9027b00 100644
--- a/internal/lsp/debug/info.go
+++ b/internal/lsp/debug/info.go
@@ -26,7 +26,7 @@
 )
 
 // Version is a manually-updated mechanism for tracking versions.
-const Version = "master"
+const Version = "v0.6.4"
 
 // ServerVersion is the format used by gopls to report its version to the
 // client. This format is structured so that the client can parse it easily.