doxygen: Disable JAVADOC_AUTOBRIEF

Disable JAVADOC_AUTOBRIEF so that we can have periods in our brief
descriptions. We always use '\brief' where we want a brief, so this won't
hide any documentation previously used as a brief.
diff --git a/doxygen/mbedtls.doxyfile b/doxygen/mbedtls.doxyfile
index d5b3abe..40fa056 100644
--- a/doxygen/mbedtls.doxyfile
+++ b/doxygen/mbedtls.doxyfile
@@ -165,7 +165,7 @@
 # comments will behave just like regular Qt-style comments
 # (thus requiring an explicit @brief command for a brief description.)
 
-JAVADOC_AUTOBRIEF      = YES
+JAVADOC_AUTOBRIEF      = NO
 
 # If the QT_AUTOBRIEF tag is set to YES then Doxygen will
 # interpret the first line (until the first dot) of a Qt-style