Added indentation to directive/variables indexes. While these files aren't designed to be read/edited by humans, indentation makes things more convenient. E.g., terminal is no longer flooded by a very long line with full list of directives if dirindex.xml is matched by grep.

DOCS =									\
		faq							\
		http/request_processing					\
		http/server_names					\
		http/configuring_https_servers				\
		debugging_log						\
		http/converting_rewrite_rules				\

FAQ =									\
		sys_errlist						\