Docs templates update and add yaml openapi support

[R0drigo-0]

Minimized Jinja2 templates by removing whitespace, condensing sections, and skipping empty optional fields.
Updated generatorto handle YAML files (.yaml, .yml) and fixed UTF-8 encoding issues.
Changed template rendering for schemas, security schemes, and content to reduce verbosity.
Updated README.md

Changes made on the docs-template-updates branch