documentation for the macro "correct_documentation"

Checks if the documentation is correct

It is defined in the file build.m4.

m4 code:

define(`correct_documentation',
`define(`_policy_makefile_increments',`
check_correct_documentation:` $(XML_DOCUMENTATION)'`'`
patsubst(`! xmllint --valid --noout $(XML_DOCUMENTATION) 2>&1 | grep .',^,
`	')'
'_policy_makefile_increments)dnl
define(`_policy_tests',_policy_tests`\
		check_correct_documentation')')