Update UDP support

[pavel-kirienko]

• The default local address (interface) should be 127.0.0.1 (currently 127.0.0.0)
• Set the default MTU to 1408 bytes as explained here https://github.com/OpenCyphal-Garage/libudpard/blob/1f5eca7057df614cdb5b4d7f6c15fef42f262a0a/libudpard/udpard.h#L53-L59
• Remove the note on setting up the capture permissions on GNU/Linux because the instructions do not work on Yukon (because the actual executable is extracted from the outer container) and are not relevant for other OSes (the note is shown on Windows as well).