Closes #5288

This refactors the filter guide docs into a single file.
Also removes out of date references to the fact that Angular used to enhance Arrays while evaluating expressions.

Before, there we multiple overview docs:
- guide/overview
- guide/introduction
- guide/dev_guide.mvc
- guide/dev_guide.mvc.understanding_model
- guide/dev_guide.mvc.understanding_view
- guide/concepts

Now we have:
- guide/introduction: High level description of Angular with the key benefits but without code or any concrete concepts
- guide/concepts: explains all important concepts with a simple example and contains deep links to the other parts of the guide.

 All the old information was moved into existing documents or deleted when they were duplicates.

Closes #4705

Closes #4690

Closes #4648

Currently, the documentation does a bad job of explaining the distinction between the services that it provides,
and the module itself. Furthermore, the instructions for using optional modules are inconsistent or missing.
This commit addresses the problem by ading a new `{@installModule foo}` annotation to the docs generator that
inlines the appropriate instructions based on the name of the module.