Update form_collections.rst

The assignment to collectionHolder must be done within jQuery ready function, or else it will be null.
BTW, the variables in JavaScript do not need the $, which is confusing since in jQuery $ has a special meaning.
Update form_collections.rst

The variable collectionHolder must be assigned inside the jQuery ready function, but must be declared outside, since it is used also in other functions.

I have put back the '$' in front of names of variables having jQuery objects as values and for uniformity, also added it to collectionHolder.
Merge pull request #3157 from attardi/patch-1

Update form_collections.rst