Incorrect code: useIncludePath()

Docs of v2.2 and later not in sync with code from v2.2 and later. See: https://github.com/symfony/ClassLoader/blob/2.2/ClassLoader.php#L108
Move curly bracket to be on the same line

This makes PSR coding standard to pass and also gives more consistency between examples (as curly brackets are on the same line).
Remove invalid tip for multiple providers

As confirmed by stof in #9734, the tip has never worked and is not going to work
Merge pull request #3296 from flip111/patch-3

Incorrect code: useIncludePath()
Merge pull request #3301 from ifdattic/patch-1

Move curly bracket to be on the same line
Merge pull request #3309 from Danez/2.1

Remove invalid tip for multiple providers
Merge branch '2.1' into 2.2

Conflicts:
	book/security.rst
Merge branch '2.2' into 2.3