Update expo snack link with only supported platforms

Author: ethanshar

uilib-docs/src/data/expoSnackLink.js

@@ -0,0 +1 @@
+export default 'https://snack.expo.io/@ethanshar/rnuilib_snack?platform=ios&supportedPlatforms=ios,android';

uilib-docs/src/pages/sections/InfoSection.jsx

@@ -1,6 +1,7 @@
 import React from 'react';
 import './InfoSection.scss';
 import qr from '../../images/newDesign/qr.png';
+import expoSnackLink from '../../data/expoSnackLink';
 
 export default () => {
   return (
@@ -24,7 +25,7 @@ export default () => {
               </a>
             </li>
             <li>
-              <a target="_blank" href="https://snack.expo.io/@ethanshar/rnuilib_snack">
+              <a target="_blank" href={expoSnackLink}>
                 Expo-Snack
               </a>
             </li>

uilib-docs/src/pages/sections/IntroSection.jsx

@@ -4,6 +4,8 @@ import './IntroSection.scss';
 import introCover from '../../images/newDesign/introCover.jpg';
 import goldStar from '../../images/goldStar.svg';
 
+import expoSnackLink from '../../data/expoSnackLink';
+
 export default () => {
   return (
     <div className="intro">
@@ -22,7 +24,7 @@ export default () => {
             <button className="dark">View Docs</button>
           </Link>
 
-          <a href="https://snack.expo.io/@ethanshar/rnuilib_snack" target="_blank" rel="noopener noreferrer">
+          <a href={expoSnackLink} target="_blank" rel="noopener noreferrer">
             <button>Expo-Snack Demo</button>
           </a>
         </div>