The endpoint macros documentation should point to the module endpoint

[cafce25]

Describe the bug
When we look at the documentation for the macro endpoint there isn't a whole lot to be seen, when it should have information about how it can be used, there is also no indication where else such information can be found.

Expected behavior
The documentation of endpoint! should be easily discoverable from it's documentation page.

Additional context
The documentation is acutally available, on the documentation page for the module endpoint so an easy fix would be to just link to it from the macros page something along the lines of

/// See the [module level documentation](mod@endpoint)

before the macros definition.