I have to answer this question:
(4) Describe whether the products incorporate or use proprietary, unpublished or non-standard cryptographic functionality, including encryption algorithms or protocols that have not been adopted or approved by a duly recognized international standards body.
My product only uses a HTTPS communication with an API, so I would like to answer by referring some standard.
So my question is: is there some standard (RFC) describing a HTTPS protocol with all of its features like SSL/TLS, different cipher suites, etc.?
HTTPS is effectively HTTP over Transport Layer Security. Although HTTPS may use other cryptographic protocols (e.g. SSL) depending on how the server is configured, most up to date servers will be running the latest TLS due to security issues found in older TLS/SSL. So rather than a specification for HTTPS, you probably need the specification for TLS.
The latest version of TLS, 1.2, was defined in RFC 5246: