Revert back to 2.28.5

git revert v2.28.5..v2.28.6
git rebase to combine the resulting revert commits

This reverts commit 3a91dad9dceb484eea8b41f8941facafc4520021.
diff --git a/doxygen/mbedtls.doxyfile b/doxygen/mbedtls.doxyfile
index 1939ac9..f6f160d 100644
--- a/doxygen/mbedtls.doxyfile
+++ b/doxygen/mbedtls.doxyfile
@@ -1,4 +1,4 @@
-PROJECT_NAME           = "Mbed TLS v2.28.6"
+PROJECT_NAME           = "Mbed TLS v2.28.5"
 OUTPUT_DIRECTORY       = ../apidoc/
 FULL_PATH_NAMES        = NO
 OPTIMIZE_OUTPUT_FOR_C  = YES