IVGCVSW-5908 Update 21.05 Doxygen Documents

 * Increment ArmNN project version number.

Signed-off-by: mathad01 <matthew.haddon@arm.com>
Change-Id: Ieefb31f563d1db655268a41f4b31c28a93a54a48
diff --git a/docs/Doxyfile b/docs/Doxyfile
index d405e28..fc28f21 100644
--- a/docs/Doxyfile
+++ b/docs/Doxyfile
@@ -61,7 +61,7 @@
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 21.02
+PROJECT_NUMBER         = 21.05
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a