chore: add note about JDK and bytecode compatibility

README.md

@@ -1,14 +1,12 @@
 named-regexp [![GitHub release](https://img.shields.io/github/release/tony19/named-regexp.svg?maxAge=2592000)](https://github.com/tony19/named-regexp/releases/) [![Build](https://github.com/tony19/named-regexp/actions/workflows/ci.yml/badge.svg)](https://github.com/tony19/named-regexp/actions/workflows/ci.yml)
 ---
 
-This lightweight library adds support for [named capture groups](http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html#groupname) in Java 5/6 (and on Android).
-
-This is a fork of the [named-regexp](http://code.google.com/p/named-regexp) project from Google Code (currently inactive).
-
+This library backports [named capture groups](http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html#groupname) from Java 7 to Java 5/6.
 
 Usage
 -----
-You can use the same constructs for named capture groups from Java 7 (i.e., `(?<name>patt)`, etc.), as in the following example:
+You can use the same constructs for named capture groups from Java 7
+(i.e., `(?<name>patt)`, etc.), as in the following example:
 
 ```java
 import com.google.code.regexp.Pattern;
@@ -54,6 +52,10 @@ $ cd named-regexp
 $ mvn package
 ```
 
+To create Java 5/6 compatible bytecode, use JDK 11 or older to build this library.
+The build automatically targets Java 8 (the minimum supported version) if using a
+newer JDK to build.
+
 Release
 -------
 
@@ -65,7 +67,8 @@ $ ./release.sh
 
 *Releases are deployed to https://repo1.maven.org/maven2/com/github/tony19/named-regexp/*
 
-To release a `SNAPSHOT` (i.e., the version in `pom.xml` ends with `-SNAPSHOT`), run the following command:
+To release a `SNAPSHOT` (i.e., the version in `pom.xml` ends with `-SNAPSHOT`),
+run the following command:
 
 ```bash
 $ mvn clean deploy