Improved docs on Post processing (or "filtering") views

I've added more thorough docs for view post processing. This wasn't very clear before. When alterations can be made with simple string functions I generally prefer this to overriding views.

Pros:

  • DRY: Don't have to maintain copy/pasted view code. You see upgrades in views immediately.
  • Will affect views even if another plugin has overridden.
  • No worries about plugin order.

Cons:

  • Core upgrade/other plugins may change markup so that your filter breaks.
  • Must be careful about your filter design and consider changes that upgrades/other plugins may make to the view