website improvements

doc/tools.txt

@@ -4,6 +4,10 @@ Tools available with Nim
 
 The standard distribution ships with the following tools:
 
+- | `Documentation generator <docs/docgen.html>`_
+  | The builtin document generator ``nim doc2`` generates HTML documentation
+    from ``.nim`` source files.
+
 - | `Nimsuggest for IDE support <nimsuggest.html>`_
   | Through the ``nimsuggest`` tool, any IDE can query a ``.nim`` source file
     and obtain useful information like definition of symbols or suggestions for

web/documentation.txt

@@ -21,6 +21,10 @@ Nim's Documentation
       | The user guide lists command line arguments, special features of the
         compiler, etc.
 
+    - | `Nim Backend Integration <docs/backends.html>`_
+      | The Backend Integeration guide gives further information of how Nim can
+        interact with C, C++, Objective C and JavaScript.
+
 
 .. container:: standout