Fix typo

Author: YoshiRulz

README.md

@@ -1,6 +1,6 @@
 # IntelliJ Idea Plugin for ANTLR v4 ![Java CI](https://github.com/antlr/intellij-plugin-v4/workflows/Java%20CI/badge.svg?branch=master) [![Latest version](https://img.shields.io/jetbrains/plugin/v/7358.svg?label=latest%20version)](https://plugins.jetbrains.com/plugin/7358) ![Downloads](https://img.shields.io/jetbrains/plugin/d/7358.svg)
 
-An [IntelliJ](https://www.jetbrains.com/idea/) 2017.1 .. 2020.3 plugin for ANTLR v4 ([plugin source at github](https://github.com/antlr/intellij-plugin-v4)).
+An [IntelliJ](https://www.jetbrains.com/idea/) 2018.3 .. 2021.x plugin for ANTLR v4 ([plugin source at github](https://github.com/antlr/intellij-plugin-v4)).
 
 [Plugin page at intellij](http://plugins.jetbrains.com/plugin/7358?pr=idea)
 

src/main/resources/META-INF/plugin.xml

@@ -7,7 +7,7 @@
   <description><![CDATA[
   <p>
       This plugin is for ANTLR v4 grammars and includes ANTLR 4.9.1. It works with
-      2017.1-2020.3.  It should work in other JetBrains IDEs.
+      2018.3-2021.x.  It should work in other JetBrains IDEs.
      </p>
 
      <ul>