Where can you find the official documentation describing HTTP protocol methods?

The official documentation describing HTTP protocol methods is found in specifications published by IETF as RFCs (Request for Comments). Key documents include:

• RFC 7230-7235 — a modern set of HTTP/1.1 specifications detailing methods, headers, status codes, and other protocol aspects.
• RFC 7540 — the HTTP/2 specification.

These documents are available on the IETF website: https://tools.ietf.org/html/rfc7231 (for example, for HTTP methods)

Additionally, for the Go language, you can refer to the documentation of the net/http package on the official Go website: https://pkg.go.dev/net/http — which describes methods and structures for working with HTTP in Go.