chore(docs): clarify comment which was copy&paste from dgeni example

It makes people happy, so why not

Closes #9798
docs(guide/*): fix typos and links

Fix some typos and link-errors introduced in
https://github.com/angular/angular.js/commit/d1ccf176351cda2b49599374c7d4ba594796012f.

Related to #9786
Closes #9800
fix(filterFilter): correctly handle deep expression objects

Previously, trying to use a deep expression object (i.e. an object whose
properties can be objects themselves) did not work correctly.
This commit refactors `filterFilter`, making it simpler and adding support
for filtering collections of arbitrarily deep objects.

Closes #9698