print_wiki.c: refine header and include a legend explaining the test state representation

Corresponding to flashrom svn r1816.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
diff --git a/print_wiki.c b/print_wiki.c
index b01ab75..85663db 100644
--- a/print_wiki.c
+++ b/print_wiki.c
@@ -29,11 +29,33 @@
 
 static const char wiki_header[] = "= Supported devices =\n\n\
 <div style=\"margin-top:0.5em; padding:0.5em 0.5em 0.5em 0.5em; \
-background-color:#eeeeee; text-align:right; border:1px solid #aabbcc;\">\
+background-color:#eeeeee; text-align:left; border:1px solid #aabbcc;\">\
 <small>\n\
-Please do '''not''' edit these tables in the wiki directly, they are \
-generated by pasting '''flashrom -z''' output.<br />\
-'''Last update:''' %s(generated by flashrom %s)\n</small></div>\n";
+'''Last update:''' %s(generated by flashrom %s)<br />\n\
+The tables below are generated from flashrom's source by copying the output of '''flashrom -z'''.<br /><br />\n\
+A short explanation of the cells representing the support state follows:<br />\n\
+{| border=\"0\" valign=\"top\"\n\
+! style=\"text-align:left;\" |\n\
+! style=\"text-align:left;\" |\n\
+|-\n\
+|{{OK}}\n\
+| The feature was '''tested and should work''' in general unless there is a bug in flashrom or another component in \
+the system prohibits some functionality.\n\
+|-\n\
+|{{Dep}}\n\
+| '''Configuration-dependent'''. The feature was tested and should work in general but there are common \
+configurations that drastically limit flashrom's capabilities or make it completely stop working.\n\
+|-\n\
+|{{?3}}\n\
+| The feature is '''untested''' but believed to be working.\n\
+|-\n\
+|{{NA}}\n\
+| The feature is '''not applicable''' in this configuration (e.g. write operations on ROM chips).\n\
+|-\n\
+|{{No}}\n\
+| The feature is '''known to not work'''. Don't bother testing (nor reporting. Patches welcome! ;).\n\
+|}\n\
+</small></div>\n";
 
 static const char th_start[] = "| valign=\"top\"|\n\n\
 {| border=\"0\" style=\"font-size: smaller\" valign=\"top\"\n\