Empty doc comments cause heaps of warnings when using Charts as an SPM dependency

## What did you do?

Added Charts as a dependency and build.

## What did you expect to happen?

No warnigns from a 3rd party dependency.

## What happened instead?

A little over a 100 warnings like
```
/Users/.../Library/Developer/Xcode/DerivedData/EvenAppen-dniaagbtvmvefbghyqwdquemkpgw/Build/Intermediates.noindex/GeneratedModuleMaps/iphoneos/Charts-Swift.h:555:20: Empty paragraph passed to '\param' command
```
## Charts Environment

**Charts version/Branch/Commit Number: latest**
**Xcode version: latest**
**Swift version: latest**
**Platform(s) running Charts: iOS**
**macOS version running Xcode: latest**

All versions are latest production releases.

---

It seems related to this issue:
https://github.com/danielgindi/Charts/issues/135

Most convenient would be a way to suppress the warnings on the entire SPM package. But I am unaware of such an option. Another option would be to give each empty doc comment content.