Update README to reflect that we require Java 11 (fixes #1690).

Author: nedtwigg

plugin-gradle/README.md

@@ -132,9 +132,10 @@ All the generic steps live in [`FormatExtension`](https://javadoc.io/doc/com.dif
 
 ### Requirements
 
-Spotless requires JRE 8+, and Gradle 6.1.1+.  Some steps require JRE 11+, `Unsupported major.minor version` means you're using a step that needs a newer JRE.
+Spotless requires JRE 11+ and Gradle 6.1.1 or newer.
 
-If you're stuck on an older version of Gradle, `id 'com.diffplug.gradle.spotless' version '4.5.1'` supports all the way back to Gradle 2.x.
+- If you're stuck on JRE 8, use [`id 'com.diffplug.spotless' version '6.13.0'` or older](https://github.com/diffplug/spotless/blob/main/plugin-gradle/CHANGES.md#6130---2023-01-14).
+- If you're stuck on an older version of Gradle, [`id 'com.diffplug.gradle.spotless' version '4.5.1'` supports all the way back to Gradle 2.x](https://github.com/diffplug/spotless/blob/main/plugin-gradle/CHANGES.md#451---2020-07-04).
 
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plugin-maven/README.md

@@ -137,7 +137,7 @@ Spotless consists of a list of formats (in the example above, `misc` and `java`)
 
 ### Requirements
 
-Spotless requires Maven to be running on JRE 8+.
+Spotless requires Maven to be running on JRE 11+. To use JRE 8, go back to [`2.30.0` or older](https://github.com/diffplug/spotless/blob/main/plugin-maven/CHANGES.md#2300---2023-01-13).
 
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