org-manual.el: Restore `load-path' for git version

* doc/org-manual.org (Using Org's git repository): Add example of
`load-path' adjustment that was earlier in the previous section
and was removed by commit f9cdda8234, so 'above' became a dangling
reference.

doc/org-manual.org

@@ -121,8 +121,11 @@ Note that in this case, =make autoloads= is mandatory: it defines
 Org's version in =org-version.el= and Org's autoloads in
 =org-loaddefs.el=.
 
-Remember to add the correct load path as described in the method
-above.
+Make sure you set the load path correctly in your Emacs init file:
+
+#+begin_src emacs-lisp
+(add-to-list 'load-path "~/src/org-mode/lisp")
+#+end_src
 
 You can also compile with =make=, generate the documentation with
 =make doc=, create a local configuration with =make config= and