Merge pull request #361 from Yubico/dev-docs

Improve developer docs

README

@@ -849,3 +849,9 @@ built artifacts.
 Official Yubico software signing keys are listed on the
 https://developers.yubico.com/Software_Projects/Software_Signing.html[Yubico
 Developers site].
+
+
+[#development]
+=== Development
+
+See the link:https://github.com/Yubico/java-webauthn-server/blob/main/doc/development.md[developer docs].

doc/development.md

@@ -2,6 +2,35 @@ Developer docs
 ===
 
 
+JDK versions
+---
+
+The project's official build JDK version is the latest LTS JDK version,
+although the project may lag behind the true latest release for a while
+until we can upgrade the build definition to match this target.
+
+The official build JDK version currently in effect is encoded in the
+["Reproducible binary"](https://github.com/Yubico/java-webauthn-server/blob/main/.github/workflows/release-verify-signatures.yml)
+workflow,
+as the JDK version is crucial for successfully reproducing released binaries.
+This version is also enforced in the release process in
+[`build.gradle`](https://github.com/Yubico/java-webauthn-server/blob/main/build.gradle).
+
+The [primary build workflow](https://github.com/Yubico/java-webauthn-server/blob/main/.github/workflows/build.yml)
+should run on all currently maintaned LTS JDK versions,
+and ideally also the latest non-LTS JDK version if Gradle and other build dependencies are compatible.
+
+A list of JDK versions and maintenance status can be found [here](https://en.wikipedia.org/wiki/Java_version_history).
+
+
+Code formatting
+---
+
+Use `./gradlew spotlessApply` to run the automatic code formatter.
+You can also run it in continuous mode as `./gradlew --continuous spotlessApply`
+to reformat whenever a file changes.
+
+
 Setup for publishing
 ---
 
@@ -16,9 +45,7 @@ ossrhPassword=bmjuyWSIik8P3Nq/ZM2G0Xs0sHEKBg+4q4zTZ8JDDRCr
 ```
 
 
-Code formatting
+Publishing a release
 ---
 
-Use `./gradlew spotlessApply` to run the automatic code formatter.
-You can also run it in continuous mode as `./gradlew --continuous spotlessApply`
-to reformat whenever a file changes.
+See the [release checklist](./releasing.md).