Drop builtin command documentation

Drop all GetTerseDocumentation and GetFullDocumentation methods from
commands.  The command documentation is now in Help/command/*.rst files.

Source/cmMacroCommand.h

@@ -59,50 +59,6 @@ public:
    */
   virtual const char* GetName() const { return "macro";}
 
-  /**
-   * Succinct documentation.
-   */
-  virtual const char* GetTerseDocumentation() const
-    {
-    return "Start recording a macro for later invocation as a command.";
-    }
-
-  /**
-   * More documentation.
-   */
-  virtual const char* GetFullDocumentation() const
-    {
-    return
-      "  macro(<name> [arg1 [arg2 [arg3 ...]]])\n"
-      "    COMMAND1(ARGS ...)\n"
-      "    COMMAND2(ARGS ...)\n"
-      "    ...\n"
-      "  endmacro(<name>)\n"
-      "Define a macro named <name> that takes arguments named "
-      "arg1 arg2 arg3 (...).  Commands listed after macro, "
-      "but before the matching endmacro, are not invoked until the macro "
-      "is invoked.  When it is invoked, the commands recorded in the "
-      "macro are first modified by replacing formal parameters (${arg1}) "
-      "with the arguments passed, and then invoked as normal commands. In "
-      "addition to referencing the formal parameters you can reference "
-      "the values ${ARGC} which will be set to the number of arguments "
-      "passed into the function as well as ${ARGV0} ${ARGV1} ${ARGV2} "
-      "... which "
-      "will have the actual values of the arguments passed in. This "
-      "facilitates creating macros with optional arguments. Additionally "
-      "${ARGV} holds the list of all arguments given to the macro and "
-      "${ARGN} "
-      "holds the list of arguments past the last expected argument. "
-      "Note that the parameters to a macro and values such as ARGN "
-      "are not variables in the usual CMake sense. They are string "
-      "replacements much like the C preprocessor would do with a macro. "
-      "If you want true CMake variables and/or better CMake scope control "
-      "you should look at the function command."
-      "\n"
-      "See the cmake_policy() command documentation for the behavior of "
-      "policies inside macros."
-      ;
-    }
   cmTypeMacro(cmMacroCommand, cmCommand);
 };