Update README.md

Author: masiulis

README.md

@@ -128,10 +128,12 @@ Underneath we use Chakra-UI, you can send in a custom theme for us to apply. Rea
 
 ```tsx
 <ReactSpreadsheetImport
-  ...
+  customTheme={yourTheme}
 />
 ```
 
+You can see all the changable styles [here](https://github.com/UgnisSoftware/react-spreadsheet-import/blob/master/src/theme.ts)
+
 ### Changing text (translations)
 
 You can change any text in the flow:
@@ -146,6 +148,8 @@ You can change any text in the flow:
 />
 ```
 
+You can see all the translation keys [here](https://github.com/UgnisSoftware/react-spreadsheet-import/blob/master/src/translationsRSIProps.ts)
+
 ## VS other libraries
 
 Flatfile vs react-spreadsheet-import and Dromo vs react-spreadsheet-import: