Update badges in the README

The update changes links of badges in README due to `master` -> `main`
branch migration.
This commit also updates the README in the src/ directory of the
package.

Author: BartoszKlonowski

README.md

@@ -5,13 +5,13 @@
     <a href="https://www.npmjs.com/package/@react-native-community/slider">
         <img src="https://img.shields.io/npm/v/@react-native-community/slider.svg" alt="Latest version released on npmjs" />
     </a>
-    <a href="https://app.circleci.com/pipelines/github/callstack/react-native-slider?branch=master">
-        <img src="https://img.shields.io/circleci/project/github/callstack/react-native-slider/master.svg" alt="Build on CircleCI" />
+    <a href="https://app.circleci.com/pipelines/github/callstack/react-native-slider?branch=main">
+        <img src="https://img.shields.io/circleci/project/github/callstack/react-native-slider/main.svg" alt="Build on CircleCI" />
     </a>
     <a href="https://github.com/callstack/react-native-slider">
         <img src="https://img.shields.io/badge/platforms-android%20|%20ios%20|%20windows%20|%20web-lightgrey.svg" alt="Supported platforms" />
     </a>
-    <a href="https://github.com/callstack/react-native-slider/blob/master/LICENSE.md">
+    <a href="https://github.com/callstack/react-native-slider/blob/main/LICENSE.md">
         <img src="https://img.shields.io/npm/l/@react-native-community/slider.svg" alt="License" />
     </a>
 </p>

src/README.md

@@ -5,13 +5,13 @@
     <a href="https://www.npmjs.com/package/@react-native-community/slider">
         <img src="https://img.shields.io/npm/v/@react-native-community/slider.svg" alt="Latest version released on npmjs" />
     </a>
-    <a href="https://app.circleci.com/pipelines/github/callstack/react-native-slider?branch=master">
-        <img src="https://img.shields.io/circleci/project/github/callstack/react-native-slider/master.svg" alt="Build on CircleCI" />
+    <a href="https://app.circleci.com/pipelines/github/callstack/react-native-slider?branch=main">
+        <img src="https://img.shields.io/circleci/project/github/callstack/react-native-slider/main.svg" alt="Build on CircleCI" />
     </a>
     <a href="https://github.com/callstack/react-native-slider">
         <img src="https://img.shields.io/badge/platforms-android%20|%20ios%20|%20windows%20|%20web-lightgrey.svg" alt="Supported platforms" />
     </a>
-    <a href="https://github.com/callstack/react-native-slider/blob/master/LICENSE.md">
+    <a href="https://github.com/callstack/react-native-slider/blob/main/LICENSE.md">
         <img src="https://img.shields.io/npm/l/@react-native-community/slider.svg" alt="License" />
     </a>
 </p>
@@ -22,7 +22,7 @@
 
 |iOS|Android|Windows|
 |:-:|:-:|:-:|
-|![iOS Screenshot](https://raw.githubusercontent.com/callstack/react-native-slider/master/.github/Examples/Slider-iOS-Example.gif)|![Android Screenshot](https://raw.githubusercontent.com/callstack/react-native-slider/master/.github/Examples/Slider-Android-Example.gif)|![Windows Screenshot](https://raw.githubusercontent.com/callstack/react-native-slider/master/.github/Examples/Slider-Windows-Example.gif)|
+|![iOS Screenshot](https://raw.githubusercontent.com/callstack/react-native-slider/main/.github/Examples/Slider-iOS-Example.gif)|![Android Screenshot](https://raw.githubusercontent.com/callstack/react-native-slider/master/.github/Examples/Slider-Android-Example.gif)|![Windows Screenshot](https://raw.githubusercontent.com/callstack/react-native-slider/main/.github/Examples/Slider-Windows-Example.gif)|
 
 ## Installation & Usage