Reverted the INPUT in doxygen to .

Previous change to include excluded the content in doxygen/input
diff --git a/doxygen/mbedtls.doxyfile b/doxygen/mbedtls.doxyfile
index 3170c80..2fc0b7f 100644
--- a/doxygen/mbedtls.doxyfile
+++ b/doxygen/mbedtls.doxyfile
@@ -664,7 +664,7 @@
 # directories like "/usr/src/myproject". Separate the files or directories
 # with spaces.
 
-INPUT                  = include
+INPUT                  = .
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding, which is