Remove obsolete reference to internal headers under include/

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

doxygen/mbedtls.doxyfile

@@ -710,7 +710,7 @@ EXCLUDE_SYMLINKS       = YES
 # against the file with absolute path, so to exclude all test directories
 # for example use the pattern */test/*
 
-EXCLUDE_PATTERNS       = *_internal.h *_wrap.h
+EXCLUDE_PATTERNS       =
 
 # The EXCLUDE_SYMBOLS tag can be used to specify one or more symbol names
 # (namespaces, classes, functions, etc.) that should be excluded from the