mod_auth_ccert/README: Add setting to ensure Prosdy asks for client certificate This used to be the default for all services, but since it triggers annoying popups in web browsers it was inverted in Prosody and only s2s enables it, so it needs to be explicitly enabled for c2s again. See trunk 115b5e32d960 Thanks debacle

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summary: Allow server administrators to probe any user
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This module lets server administrators send `<presence type="probe"/>`
to any local user and receive their presence in response, bypassing
roster checks.