[FIX] *: RST cleanup

RST cleanup to comply with the RST guidelines. This is required so we
can use "make test", as there are currently hundreds of errors. For now,
it is unusable because of the oldest code in this repo.

closes odoo/documentation#3581

Signed-off-by: Castillo Jonathan (jcs) <jcs@odoo.com>

content/developer/reference/frontend/javascript_modules.rst

@@ -263,7 +263,7 @@ within the same Odoo addon.
 .. _frontend/modules/odoo_module:
 
 Odoo Module System
-===================
+==================
 
 Odoo has defined a small module system (located in the file
 :file:`addons/web/static/src/js/boot.js`, which needs to be loaded first). The Odoo
@@ -371,7 +371,7 @@ If an error happens, it will be logged (in debug mode) in the console:
   Modules who depend on a missing or a failed module
 
 Asynchronous modules
----------------------
+--------------------
 
 It can happen that a module needs to perform some work before it is ready.  For
 example, it could do an rpc to load some data.  In that case, the module can