Ignore windows generated manifests

- Commit a95ce7f builds *.manifest files on windows -- added them to
  .gitignore.

- ignore pod -> html temp file
Reviewed-by: NMatt Caswell <matt@openssl.org>
Reviewed-by: NRichard Levitte <levitte@openssl.org>

.gitignore

@@ -169,3 +169,7 @@ Makefile.save
 *.bak
 cscope.*
 *.d
+pod2htmd.tmp
+
+# Windows manifest files
+*.manifest