[ADD] explanation + interaction of journals + chart of accounts

After discussion with fp this probably isn't the direction (ish), but
want to checkpoint this in order to work on other stuff earlier in the
document, but not commit a single gigantic blob of stuff.

conf.py

@@ -265,5 +265,8 @@ texinfo_documents = [
 #texinfo_no_detailmenu = False
 
 def setup(app):
+    app.add_javascript('atom.js')
+    app.add_javascript('immutable.js')
     app.add_javascript('react.js')
-    app.add_javascript('accounting.js')
+    app.add_javascript('chart-of-accounts.js')
+    app.add_javascript('fiscalyear.js')