docs: Fix variable name in custom-matcher-api code example

CHANGELOG.md

@@ -22,6 +22,7 @@
 - `[docs]` Add example to `jest.requireActual` ([#8482](https://github.com/facebook/jest/pull/8482)
 - `[docs]` Add example to `jest.mock` for mocking ES6 modules with the `factory` parameter ([#8550](https://github.com/facebook/jest/pull/8550))
 - `[docs]` Add information about using `jest.doMock` with ES6 imports ([#8573](https://github.com/facebook/jest/pull/8573))
+- `[docs]` Fix variable name in custom-matcher-api code example ([#8582](https://github.com/facebook/jest/pull/8582))
 
 ### Performance
 

docs/ExpectAPI.md

@@ -172,13 +172,13 @@ expect.extend({
           `Expected: ${this.utils.printExpected(expected)}\n` +
           `Received: ${this.utils.printReceived(received)}`
       : () => {
-          const difference = diff(expected, received, {
+          const diffString = diff(expected, received, {
             expand: this.expand,
           });
           return (
             this.utils.matcherHint('toBe', undefined, undefined, options) +
             '\n\n' +
-            (difference && difference.includes('- Expect')
+            (diffString && diffString.includes('- Expect')
               ? `Difference:\n\n${diffString}`
               : `Expected: ${this.utils.printExpected(expected)}\n` +
                 `Received: ${this.utils.printReceived(received)}`)

website/versioned_docs/version-24.0/ExpectAPI.md

@@ -173,13 +173,13 @@ expect.extend({
           `Expected: ${this.utils.printExpected(expected)}\n` +
           `Received: ${this.utils.printReceived(received)}`
       : () => {
-          const difference = diff(expected, received, {
+          const diffString = diff(expected, received, {
             expand: this.expand,
           });
           return (
             this.utils.matcherHint('toBe', undefined, undefined, options) +
             '\n\n' +
-            (difference && difference.includes('- Expect')
+            (diffString && diffString.includes('- Expect')
               ? `Difference:\n\n${diffString}`
               : `Expected: ${this.utils.printExpected(expected)}\n` +
                 `Received: ${this.utils.printReceived(received)}`)