[webview] Fix typos in the README (flutter#4249)

Author: wytesk133

packages/webview_flutter/webview_flutter/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.1.2
+
+* Fix typos in the README.
+
 ## 2.1.1
 
 * Fixed `_CastError` that was thrown when running the example App.

packages/webview_flutter/webview_flutter/README.md

@@ -23,8 +23,8 @@ Here are some points to consider when choosing between the two:
 
 * *Hybrid composition* mode has a built-in keyboard support while *Virtual displays* mode has multiple
 [keyboard issues](https://github.com/flutter/flutter/issues?q=is%3Aopen+label%3Avd-only+label%3A%22p%3A+webview-keyboard%22)
-* *Hybrid composition* mode requires Android SKD 19+ while *Virtual displays* mode requires Android SDK 20+
-* *Hybrid composition* mode has [performence limitations](https://flutter.dev/docs/development/platform-integration/platform-views#performance) when working on Android versions prior to Android 10 while *Virtual displays* is performant on all supported Android versions 
+* *Hybrid composition* mode requires Android SDK 19+ while *Virtual displays* mode requires Android SDK 20+
+* *Hybrid composition* mode has [performance limitations](https://flutter.dev/docs/development/platform-integration/platform-views#performance) when working on Android versions prior to Android 10 while *Virtual displays* is performant on all supported Android versions 
 
 |                             | Hybrid composition  | Virtual displays |
 | --------------------------- | ------------------- | ---------------- |

packages/webview_flutter/webview_flutter/pubspec.yaml

@@ -2,7 +2,7 @@ name: webview_flutter
 description: A Flutter plugin that provides a WebView widget on Android and iOS.
 repository: https://github.com/flutter/plugins/tree/master/packages/webview_flutter/webview_flutter
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+webview%22
-version: 2.1.1
+version: 2.1.2
 
 environment:
   sdk: ">=2.14.0 <3.0.0"