DOC: config: mention that section 8.6 does not apply to the cbor encoding

DOC: config: mention that section 8.6 does not apply to the cbor encoding

Section 8.6 of the config manual explains that the characters outside
the 32..126 range are not emitted as-is in the logs but encoded as a '#'
followed by their two hex digits, so that a log line cannot upset a
terminal.

However, this doesn't apply to cbor output, which can come as a surprise
to the reader. The reason is that cbor output already emits all bytes as
hex chars by default (hence the protection is granted), but supports raw
mode with "+bin" in which case the output will be consumed by a suitable
cbor parser and not by a terminal. In such a case we want the output to
remain verbatim and certainly not to be escaped. So let's update the doc
to explain this.