Improve the missing rust-analyzer bin error notification (#172)

Author: alexheretic

lib/index.js

@@ -80,7 +80,11 @@ function rustupRun(toolchain, command, opts={}) {
 
 function notifyLanguageServerCommandFailed(languageServerCmd) {
   clearIdeRustNotifications("ide-rust.langServerCommand")
-  atom.notifications.addError(`Language server command \`${languageServerCmd}\` failed`, {
+  let description = "Make sure the **rust-analyzer** binary is installed  and in `$PATH`."
+    + "\n\nSee https://rust-analyzer.github.io/manual.html#rust-analyzer-language-server-binary."
+
+  atom.notifications.addError(`Could not run \`${languageServerCmd}\``, {
+    description,
     dismissable: true,
     _src: "ide-rust.langServerCommand"
   })