kernel-doc: generate main index page when building 'htmldocs'

A patch for kernel-doc that enables the generation of a global, TOC-like
index.html page after building 'htmldocs'
Signed-off-by: Borislav Petkov <bbpetkov@yahoo.de>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/DocBook/Makefile

@@ -43,6 +43,7 @@ pdfdocs: $(PDF)
 
 HTML := $(sort $(patsubst %.xml, %.html, $(BOOKS)))
 htmldocs: $(HTML)
+	$(call build_main_index)
 
 MAN := $(patsubst %.xml, %.9, $(BOOKS))
 mandocs: $(MAN)
@@ -132,10 +133,17 @@ quiet_cmd_db2pdf = PDF      $@
 %.pdf : %.xml
 	$(call cmd,db2pdf)
 
+
+main_idx = Documentation/DocBook/index.html
+build_main_index = rm -rf $(main_idx) && \
+		   echo '<h1>Linux Kernel HTML Documentation</h1>' >> $(main_idx) && \
+		   echo '<h2>Kernel Version: $(KERNELVERSION)</h2>' >> $(main_idx) && \
+		   cat $(HTML) >> $(main_idx)
+
 quiet_cmd_db2html = HTML   $@
       cmd_db2html = xmlto xhtml $(XMLTOFLAGS) -o $(patsubst %.html,%,$@) $< && \
 		echo '<a HREF="$(patsubst %.html,%,$(notdir $@))/index.html"> \
-         Goto $(patsubst %.html,%,$(notdir $@))</a><p>' > $@
+        $(patsubst %.html,%,$(notdir $@))</a><p>' > $@
 
 %.html:	%.xml
 	@(which xmlto > /dev/null 2>&1) || \