Exclude README.md from Doxygen

doxygen warns about the <img> inside the <a> element which
contains the graphic for the Travis CI build status.

Doxyfile.in

@@ -875,6 +875,7 @@ RECURSIVE              = NO
 # run.
 
 EXCLUDE                =
+EXCLUDE                += README.md
 
 # The EXCLUDE_SYMLINKS tag can be used to select whether or not files or
 # directories that are symbolic links (a Unix file system feature) are excluded
@@ -892,7 +893,6 @@ EXCLUDE_SYMLINKS       = NO
 
 EXCLUDE_PATTERNS       =
 EXCLUDE_PATTERNS      += *-usage.c
-EXCLUDE_PATTERNS      += *.md
 
 # The EXCLUDE_SYMBOLS tag can be used to specify one or more symbol names
 # (namespaces, classes, functions, etc.) that should be excluded from the