[FIX] plug chart of accounts & journal entries widgets on explicit classes

Sections get an id automatically generated from the title, "journal
entries" and "chart of accounts" are pretty generic concepts, so the
widgets looking for these ids can get enabled on sections they're not
intended to live in.

On the other hand, Sphinx is not likely to generically create classes
for these concepts without being explicitly prompted (via
e.g. rst-class).

_static/chart-of-accounts.js

@@ -133,7 +133,7 @@
     });
 
     document.addEventListener('DOMContentLoaded', function () {
-        var chart = document.getElementById('chart-of-accounts');
+        var chart = findAncestor(document.querySelector('.chart-of-accounts'), 'section');
         if (!chart) { return; }
 
         var controls = document.createElement('div');