docs: Add sketch-feather to "Related Projects" section (#219)

README.md

@@ -270,6 +270,7 @@ Caught a mistake or want to contribute to the documentation? [Edit this page on
  - [angular-feather](https://github.com/michaelbazos/angular-feather) - Feather icons for Angular applications
  - [elm-feather](https://github.com/1602/elm-feather) - Feather icons for Elm applications
  - [react-feather](https://github.com/carmelopullara/react-feather) - Feather icons as React components
+ - [sketch-feather](https://github.com/odmln/sketch-feather) - Feather icons as a Sketch library
  - [vue-feather-icon](https://github.com/mage3k/vue-feather-icon) - Feather icons as Vue components
 
 ## License