Improvements to Application docs

[piotr-cz]

Described some things that are not obvious from the docblocks.

I'm confused, what is supposed to come into README.md's. Now we have

• There is an API documentation
• Framework GitHub page with obsolete documentation
• Experimental developer documentation which is aggregating the README's and adding the Recipes

[dongilbert]

Could you also update line 97 to say Monolog instead of Logger. The Logger class doesn't exist in the context of that example. After that, I think it's good to merge.

[piotr-cz]

@dongilbert Actually I think that the Monolog class doesn't exist, see Monolog > Logger.php so it's the use statement at line 78 that needs an update:

use Monolog\Logger;

[dongilbert]

Good catch, I was just going off memory and what I saw. Thanks @piotr-cz.