Add swagger API documentation as a central standardized place for all api endpoints

[jb-io]

Tried to collect all API information from various places:

• https://github.com/steff393/wbec/blob/master/README.md
• https://github.com/steff393/wbec/blob/master/src/webServer.cpp
• https://github.com/steff393/wbec/wiki/Webserver-sitemap

Created a machine readable api documentation accodring to standards. Human Readable Version can be generated on swagger.io

Links before accepting Merge Request:

• Editor: https://editor.swagger.io/?url=https://raw.githubusercontent.com/jb-io/wbec/add-swagger-documentation/api.swagger.yaml
• Viewer: https://petstore.swagger.io/?url=https://raw.githubusercontent.com/jb-io/wbec/add-swagger-documentation/api.swagger.yaml

After Merge Request:

• Editor: https://editor.swagger.io/?url=https://raw.githubusercontent.com/steff393/wbec/master/api.swagger.yaml
• Viewer: https://petstore.swagger.io/?url=https://raw.githubusercontent.com/steff393/wbec/master/api.swagger.yaml