Specify that you need to call `--doctool` from the Godot root directory (#4920)

Co-authored-by: Hugo Locurcio <[email protected]>

community/contributing/updating_the_class_reference.rst

@@ -65,10 +65,8 @@ When you create a new class or modify the engine's API, you need to re-generate
 
 To do so, you first need to compile Godot. See the
 :ref:`doc_introduction_to_the_buildsystem` page to learn how. Then, execute the
-compiled godot executable with the ``--doctool`` option. For example, if you're on 64-bit
-Linux the command is:
-
-::
+compiled Godot binary from the Godot root directory with the ``--doctool`` option.
+For example, if you're on 64-bit Linux, the command is::
 
     ./bin/godot.linuxbsd.tools.64 --doctool