Fix typos in rend-spec-ng.txt and tor-spec.txt

There are a number of typos and inconsistencies in in torspec/proposals/224-rend-spec-ng.txt. I've created a branch to fix them:

Branch: typos-rend-spec-ng Repository: https://github.com/teor2345/torspec.git Changes:

• Fix misspellings, inconsistent field names, and missing INT_8() specifiers. (Inferred from context.)
• Consistently use _LEN rather than _LENGTH for field lengths in 224-rend-spec-ng.txt. (8 replacements made.)

There is also a typo in torspec/tor-spec.txt that is fixed in:

Branch: typos-tor-spec Repository: https://github.com/teor2345/torspec.git Changes:

• Fix typo where "yes" is clearly intended to be "yet"