Add Comprehensive API Endpoint Technical Specification to README#1

Alexdyn1927 wants to merge 4 commits intoutukku77:4d810639-6ca5-41cf-a792-1ee6c2a3763dutukku77/test-case:4d810639-6ca5-41cf-a792-1ee6c2a3763dfrom

Alexdyn1927:api-endpoint-technical-spec-1749133421Alexdyn1927/test-case:api-endpoint-technical-spec-1749133421Copy head branch name to clipboard