Comment thumbThintColor about conflicts with thumbImage

This commit closes #346
It adds the note to the `thumbTintColor` property in docs regarding the conflicts with the `thumbImage` prop.
Both these props work correctly, however using them both at the same time may result (on some platforms) in the image not working properly.

Author: BartoszKlonowski

README.md

@@ -100,7 +100,7 @@ To use this library you need to ensure you are using the correct version of Reac
 | `tapToSeek` | Permits tapping on the slider track to set the thumb position.<br/>Defaults to false on iOS. No effect on Android or Windows. | bool | No | iOS |
 | `inverted` | Reverses the direction of the slider.<br/>Default value is false. | bool | No | |
 | `vertical` | Changes the orientation of the slider to vertical, if set to `true`.<br/>Default value is false. | bool | No | Windows |
-| `thumbTintColor` | Color of the foreground switch grip. | [color](https://reactnative.dev/docs/colors) | No | Android |
+| `thumbTintColor` | Color of the foreground switch grip.<br/>**NOTE:** This prop will override the `thumbImage` prop set, meaning that if both `thumbImage` and `thumbTintColor` will be set, image used for the thumb may not be displayed correctly! | [color](https://reactnative.dev/docs/colors) | No | Android |
 | `maximumTrackImage` | Assigns a maximum track image. Only static images are supported. The leftmost pixel of the image will be stretched to fill the track. | Image<br/>.propTypes<br/>.source | No | iOS |
 | `minimumTrackImage` | Assigns a minimum track image. Only static images are supported. The rightmost pixel of the image will be stretched to fill the track. | Image<br/>.propTypes<br/>.source | No | iOS |
 | `thumbImage` | Sets an image for the thumb. Only static images are supported. Needs to be a URI of a local or network image; base64-encoded SVG is not supported. | Image<br/>.propTypes<br/>.source | No | |