Doc updates to include additional ALPN extension values

[giddij01]

Overview

Adding examples to cover space character (sp, 0x20) handling in the ALPN Extension Value as we have seen some unexpected JA4 fingerprints in Wireshark when a space character is sent by the client.

Please note, I have raised a an issue over on the Wireshark repo to highlight what we have seen: https://gitlab.com/wireshark/wireshark/-/issues/20966

Example 1

ALPN Extension Value sent by client:

ALPN Next Protocol: ' ' 
Hex values: 0x20

Resulting JA4 Fingerprint (Note: double space in place of ALPN value)

t13d0808  _b83013aef563_36a8af52ae46

Expected JA4 Fingerprint

t13d080820_b83013aef563_36a8af52ae46

Example 2

ALPN Extension Value sent by client:

ALPN Next Protocol: 'a ' 
Hex values: 0x61 0x20

Resulting JA4 Fingerprint (Note: sinlge space set for second ALPN value)

t13d0808a _b83013aef563_36a8af52ae46

Expected JA4 Fingerprint

t13d080860_b83013aef563_36a8af52ae46

[johnthacker]

While you do clarify with the exact hex values, it might be worth putting the word "ASCII" in there somewhere when saying alphanumeric (since RFC 7301 clearly anticipates UTF-8 strings (which are not used.)