kbuild: doc: remove documentation about copying Module.symvers around

		will then do the expected and compile both modules with

		full knowledge of symbols from either module.

	Use an extra Module.symvers file

		When an external module is built, a Module.symvers file

		is generated containing all exported symbols which are

		not defined in the kernel. To get access to symbols

		from bar.ko, copy the Module.symvers file from the

		compilation of bar.ko to the directory where foo.ko is

		built. During the module build, kbuild will read the

		Module.symvers file in the directory of the external

		module, and when the build is finished, a new

		Module.symvers file is created containing the sum of

		all symbols defined and not part of the kernel.

	Use "make" variable KBUILD_EXTRA_SYMBOLS

		If it is impractical to add a top-level kbuild file,

		you can assign a space separated list