Inconsistent OpenAPI Specification

[FrankLindert]

We found two issues with the documentation:

• the X-total Header is also necessary for the "/categories/tree" route because the function BridgeRequest.getItems() is used in EcomBridgeAPI.getCategoriesTree().
• the calls to get the categories, products or content pages use trailing slashes (e.g. "/categories/"), in the openAPI it ist defined with "/categories". In frameworks like next.js this is a big difference.