Update readme for integer values (#382)

Author: Nakira

README.md

@@ -96,10 +96,10 @@ Starts the camera preview instance.
 | Option                       | values        | descriptions                                                                                                                                                             |
 | ---------------------------- | ------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
 | position                     | front \| rear | Show front or rear camera when start the preview. Defaults to front                                                                                                      |
-| width                        | number        | (optional) The preview width in pixels, default window.screen.width (applicable to the android and ios platforms only)                                                   |
-| height                       | number        | (optional) The preview height in pixels, default window.screen.height (applicable to the android and ios platforms only)                                                 |
-| x                            | number        | (optional) The x origin, default 0 (applicable to the android and ios platforms only)                                                                                    |
-| y                            | number        | (optional) The y origin, default 0 (applicable to the android and ios platforms only)                                                                                    |
+| width                        | number (integer !)       | (optional) The preview width in pixels, default window.screen.width (applicable to the android and ios platforms only)                                                   |
+| height                       | number (integer !)       | (optional) The preview height in pixels, default window.screen.height (applicable to the android and ios platforms only)                                                 |
+| x                            | number    (integer !)    | (optional) The x origin, default 0 (applicable to the android and ios platforms only)                                                                                    |
+| y                            | number    (integer !)    | (optional) The y origin, default 0 (applicable to the android and ios platforms only)                                                                                    |
 | toBack                       | boolean       | (optional) Brings your html in front of your preview, default false (applicable to the android and ios platforms only)                                                   |
 | paddingBottom                | number        | (optional) The preview bottom padding in pixes. Useful to keep the appropriate preview sizes when orientation changes (applicable to the android and ios platforms only) |
 | rotateWhenOrientationChanged | boolean       | (optional) Rotate preview when orientation changes (applicable to the ios platforms only; default value is true)                                                         |