Update PROJECT_NUMBER in Doxyfile for 22.08

Signed-off-by: Nikhil Raj <nikraj01@e126673.cambridge.arm.com>
Change-Id: I2446013092221f3016f8d2d57256ea0f384d0cec
diff --git a/docs/Doxyfile b/docs/Doxyfile
index 65cb404..efd34f6 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         = 22.05.01
+PROJECT_NUMBER         = 22.08
 
 # 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