[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#3567

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

content/developer/reference/javascript/javascript_cheatsheet.rst

@@ -280,12 +280,13 @@ using the view in the kanban arch (a specific example is the helpdesk dashboard)
     need to have a valid arch field.
 
 Promises and asynchronous code
-===============================
+==============================
 
 For a very good and complete introduction to promises, please read this excellent article https://github.com/getify/You-Dont-Know-JS/blob/1st-ed/async%20%26%20performance/ch3.md
 
 Creating new Promises
------------------------
+---------------------
+
 - turn a constant into a promise
     There are 2 static functions on Promise that create a resolved or rejected promise based on a constant:
 
@@ -383,6 +384,7 @@ Creating new Promises
 
 Waiting for Promises
 --------------------
+
 - waiting for a number of Promises
         if you have multiple promises that all need to be waited, you can convert them into a single promise that will be resolved when all the promises are resolved using Promise.all(arrayOfPromises).
 
@@ -486,7 +488,7 @@ Error handling
 
 
 Testing asynchronous code
---------------------------
+-------------------------
 
 - using promises in tests
         In the tests code, we support the latest version of Javascript, including primitives like `async` and `await`. This makes using and waiting for promises very easy.