docs: cite RFC 9110 for idempotent method list

packages/server/lib/cloud/network/is_retryable_error.ts

@@ -5,9 +5,12 @@ import { isNonRetriableCertErrorCode } from './non_retriable_cert_error_codes'
 
 const debug = Debug('cypress-verbose:server:is-retryable-error')
 
+// Per RFC 9110 §9.2.2, PUT, DELETE, and safe methods (GET, HEAD, OPTIONS, TRACE
+// from §9.2.1) are idempotent. TRACE is omitted here because it is not used by
+// any cloud API caller and is commonly disabled for security reasons.
+// https://www.rfc-editor.org/rfc/rfc9110#section-9.2.2
 const IDEMPOTENT_METHODS = new Set(['GET', 'HEAD', 'PUT', 'DELETE', 'OPTIONS'])
 
-// Status codes safe to retry regardless of method.
 const ALWAYS_RETRYABLE_STATUSES = [408, 429, 502, 503, 504]
 
 // Additional statuses that are only safe to retry on idempotent methods —