Rewrite README with usage, status and version guidance

README.md

@@ -1,25 +1,77 @@
-Modello
-=======
+# Modello
 
-[![Maven Central](https://img.shields.io/maven-central/v/org.codehaus.modello/modello.svg?label=Maven%20Central)](https://search.maven.org/artifact/org.codehaus.modello/modello)
-[![MIT License](https://img.shields.io/github/license/codehaus-plexus/modello.svg?label=License)](http://www.apache.org/licenses/)
-![Build Status](https://github.com/codehaus-plexus/modello/workflows/GitHub%20CI/badge.svg)
+[![Maven Central](https://img.shields.io/maven-central/v/org.codehaus.modello/modello-maven-plugin.svg?label=Maven%20Central)](https://central.sonatype.com/artifact/org.codehaus.modello/modello-maven-plugin)
+[![GitHub CI](https://github.com/codehaus-plexus/modello/workflows/GitHub%20CI/badge.svg)](https://github.com/codehaus-plexus/modello/actions)
 [![Reproducible Builds](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/jvm-repo-rebuild/reproducible-central/master/content/org/codehaus/modello/badge.json)](https://github.com/jvm-repo-rebuild/reproducible-central/blob/master/content/org/codehaus/modello/README.md)
+[![MIT License](https://img.shields.io/github/license/codehaus-plexus/modello.svg?label=License)](https://opensource.org/licenses/mit-license.php)
 
-Modello is a framework for code generation from a simple model.
+Code generation from a single model file. You describe your data model once in an `.mdo` file, and Modello
+generates the Java classes, the readers and writers, an XSD and the documentation — all kept in step,
+because they come from the same source.
 
-Modello generates code from a simple model format: based on a plugin architecture, various types of code and descriptors can be generated from the single model, including Java POJOs, XML/JSON/YAML marshallers/unmarshallers, XSD and documentation.
+Maven uses it for its own POM and `settings.xml` models.
 
-# Documentation
+## Status
 
-Documentation can be found on the Modello site hosted at [Github.io](http://codehaus-plexus.github.io/modello/).
+Maintained. Generated code is consumed widely, so output compatibility is treated carefully.
 
-This site is generated by running:
+## Using it
 
+Modello is a build-time tool, so it goes in `<build><plugins>` rather than in your dependencies:
+
+```xml
+<plugin>
+  <groupId>org.codehaus.modello</groupId>
+  <artifactId>modello-maven-plugin</artifactId>
+  <version>2.7.0</version>
+  <configuration>
+    <version>1.0.0</version>
+    <models>
+      <model>src/main/mdo/my-model.mdo</model>
+    </models>
+  </configuration>
+  <executions>
+    <execution>
+      <goals>
+        <goal>java</goal>
+        <goal>xpp3-reader</goal>
+        <goal>xpp3-writer</goal>
+        <goal>xsd</goal>
+      </goals>
+    </execution>
+  </executions>
+</plugin>
 ```
-mvn -Prun-its,reporting clean verify site site:stage
-```
 
-# Licensing
+Check the badge above for the current version. Each goal is a generator; pick the ones you need.
+
+## Generators
+
+Java classes, plus readers and writers for XML (XPP3, StAX, SAX, DOM4J, JDOM), YAML (SnakeYaml, Jackson)
+and JSON Schema, plus XSD, xdoc documentation and version converters. Velocity templates are supported
+since 2.1.0 for anything not covered.
+
+Each has its own page under [Plugins](https://codehaus-plexus.github.io/modello/) on the site.
+
+## Requirements
+
+Java 8 or later.
+
+## Documentation
+
+- [Project site](https://codehaus-plexus.github.io/modello/) — the model descriptor reference, generator pages and a [migration guide](https://codehaus-plexus.github.io/modello/migration-guide.html)
+- [Release notes](https://github.com/codehaus-plexus/modello/releases)
+
+## Licensing
+
+Modello is licensed under the [MIT License](https://opensource.org/licenses/mit-license.php). The rest of
+the Codehaus Plexus projects are Apache-2.0.
+
+## Contributing
+
+See [CONTRIBUTING.md](https://github.com/codehaus-plexus/.github/blob/master/CONTRIBUTING.md). In short:
+`mvn verify` builds, and run `mvn spotless:apply` before pushing or CI will fail on formatting. Integration
+tests run under `-Prun-its`.
 
-Modello is licensed under the therms of the [MIT License](http://opensource.org/licenses/mit-license.php)
+Please report security vulnerabilities privately — see
+[SECURITY.md](https://github.com/codehaus-plexus/.github/blob/master/SECURITY.md), not a public issue.