mod_http_upload: Update compatibility information At least 0.9.x is broken due to use of util.jid.host, and I didn't check 0.10.x since that branch is also obsolete. Added info about mod_http_file_share.

This module blocks configured queries that change server state.

E.g. to make vCard storage read-only:

``` lua
readonly_stores = {
	vcard = { "vcard-temp", "vCard" };
}
```