Improve QSslConfiguration::peerVerifyDepth() , setPeerVerifyDepth() documentation

QSslConfiguration::peerVerifyDepth(), QSslConfiguration::setPeerVerifyDepth() documentation could be improved:

• The documentation says the default for peerVerifyDepth is 0, and that "0 [...] indicate[s] that the whole certificate chain should be checked." This seems not the case for the OpenSSL backend, as the OpenSSL documentation claims "The default depth limit is 100, allowing for the peer certificate, at most 100 intermediate CA certificates and a final trust anchor certificate. ".

• The documentation is unclear on what happens if the depth is reached. It could be derived that, in this case, a certificate is just accepted, while the OpenSSL documentation hints that an error will be raised. For the TLS backend, it seems it is ignored though .