Merge pull request #5800 from ethereum/wip/faq-call

[DOCS] Add call warning into main docs and remove FAQ item

docs/frequently-asked-questions.rst

@@ -54,18 +54,6 @@ Yes, you can use ``abi.encodePacked``::
         }
     }
 
-
-Why is the low-level function ``.call()`` less favorable than instantiating a contract with a variable (``ContractB b;``) and executing its functions (``b.doSomething();``)?
-=============================================================================================================================================================================
-
-If you use actual functions, the compiler will tell you if the types
-or your arguments do not match, if the function does not exist
-or is not visible and it will do the packing of the
-arguments for you.
-
-See `ping.sol <https://github.com/fivedogit/solidity-baby-steps/blob/master/contracts/45_ping.sol>`_ and
-`pong.sol <https://github.com/fivedogit/solidity-baby-steps/blob/master/contracts/45_pong.sol>`_.
-
 What happens if you send ether along with a function call to a contract?
 ========================================================================
 

docs/units-and-global-variables.rst

@@ -199,6 +199,10 @@ Members of Address Types
 
 For more information, see the section on :ref:`address`.
 
+.. warning::
+    You should avoid using ``.call()`` whenever possible when executing another contract function as it bypasses type checking,
+    function existence check, and argument packing.
+
 .. warning::
     There are some dangers in using ``send``: The transfer fails if the call stack depth is at 1024
     (this can always be forced by the caller) and it also fails if the recipient runs out of gas. So in order