internal/lsp/protocol: use correct JSON name for RootURI

According to the spec,

https://microsoft.github.io/language-server-protocol/specification#initialize

the JSON name of the RootURI field is "rootUri", not "rootURI".

Change-Id: I187be9e517a6c70dabc09de4215326f2555c3f1c
Reviewed-on: https://go-review.googlesource.com/c/153537
Reviewed-by: Ian Cottrell <iancottrell@google.com>
Run-TryBot: Ian Cottrell <iancottrell@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

internal/lsp/protocol/general.go

@@ -33,11 +33,11 @@ type InitializeParams struct {
 	RootPath *string `json:"rootPath"`
 
 	/**
-	 * The rootURI of the workspace. Is null if no
-	 * folder is open. If both `rootPath` and `rootURI` are set
-	 * `rootURI` wins.
+	 * The rootUri of the workspace. Is null if no
+	 * folder is open. If both `rootPath` and `rootUri` are set
+	 * `rootUri` wins.
 	 */
-	RootURI *DocumentURI `json:"rootURI"`
+	RootURI *DocumentURI `json:"rootUri"`
 
 	/**
 	 * User provided initialization options.