Add docs for runCommand + container
Add docs for runCommand + container

Add notes on the limitations of runCommand() and the container.
Because commands don't have access to the container they are unable
resolve dependencies. Instead commands should be defined in the
container and then resolved as dependencies to the calling command.

ndm2/cakephp,ndm2/cakephp,cakephp/cakephp,ADmad/cakephp,CakeDC/cakephp,ndm2/cakephp,ADmad/cakephp,CakeDC/cakephp,ADmad/cakephp,ndm2/cakephp,CakeDC/cakephp,cakephp/cakephp,cakephp/cakephp,cakephp/cakephp,CakeDC/cakephp,ADmad/cakephp