Add docs for set_default_verify_paths

        wrap_ssl_result(unsafe { ffi_extras::SSL_CTX_set_tmp_dh(self.ctx, dh.raw()) as i32 })

    }

    /// Use the default locations of trusted certificates for verification.

    ///

    /// These locations are read from the `SSL_CERT_FILE` and `SSL_CERT_DIR`

    /// environment variables if present, or defaults specified at OpenSSL

    /// build time otherwise.

    pub fn set_default_verify_paths(&mut self) -> Result<(), SslError> {

        wrap_ssl_result(unsafe { ffi::SSL_CTX_set_default_verify_paths(self.ctx) })

    }