Collection of RFCs and references that I keep forgeting about and spend tons of time finding them on and on again.
- request line: https://www.rfc-editor.org/rfc/rfc7230#section-3.1
- header fields: https://www.rfc-editor.org/rfc/rfc7230#section-3.2
- basic rules (VCHAR etc.): https://www.rfc-editor.org/rfc/rfc5234#appendix-B.1