add internal default tooltip text

Editor/Rstudio.d.ts

@@ -13,7 +13,9 @@ declare namespace rstudio.tooltip {
     };
     function contentHtml(word: string): string;
     const imports_keyword: string;
+    const return_keyword: string;
     const keywords: {
         imports: string;
+        return: string;
     };
 }

Editor/rstudio/rstudio/tooltip.ts

@@ -48,7 +48,14 @@ module rstudio.tooltip {
         'Loading/attaching of the .NET clr package module',
         'similar to the <code>library</code> and <code>require</code> load and attach add-on .NET clr package modules.');
 
+    export const return_keyword = tooltip(
+        'Returns the function value to caller',
+        `If value is missing, NULL is returned. If it is a single expression, the value of the evaluated expression is returned. 
+(The expression is evaluated as soon as return is called, in the evaluation frame of the function and before any on.exit expression is evaluated.)
+If the end of a function is reached without calling return, the value of the last evaluated expression is returned.`);
+
     export const keywords = {
-        "imports": imports_keyword
+        "imports": imports_keyword,
+        'return': return_keyword
     };
 }