Improve README

README.md

@@ -1,4 +1,4 @@
-# PMD
+# PMD - source code analyzer
 
 [![Join the chat at https://gitter.im/pmd/pmd](https://badges.gitter.im/pmd/pmd.svg)](https://gitter.im/pmd/pmd?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![Build Status](https://github.com/pmd/pmd/workflows/build/badge.svg?branch=master)](https://github.com/pmd/pmd/actions)
@@ -7,18 +7,73 @@
 [![Coverage Status](https://coveralls.io/repos/github/pmd/pmd/badge.svg)](https://coveralls.io/github/pmd/pmd)
 [![Codacy Badge](https://api.codacy.com/project/badge/Grade/a674ee8642ed44c6ba7633626ee95967)](https://www.codacy.com/app/pmd/pmd?utm_source=github.com&utm_medium=referral&utm_content=pmd/pmd&utm_campaign=Badge_Grade)
 [![Contributor Covenant](https://img.shields.io/badge/Contributor%20Covenant-v2.0%20adopted-ff69b4.svg)](code_of_conduct.md) 
-
-## About
+[![Documentation (latest)](https://img.shields.io/badge/docs-latest-green)](https://pmd.github.io/latest/)
 
 **PMD** is a source code analyzer. It finds common programming flaws like unused variables, empty catch blocks,
-unnecessary object creation, and so forth. It supports Java, JavaScript, Salesforce.com Apex and Visualforce,
+unnecessary object creation, and so forth. It supports many languages. It can be extended with custom rules.
+It uses JavaCC and Antlr for parsing source into AST and runs rules against it to find violations.
+Rules can be written in Java or using a XPath query.
+
+It supports Java, JavaScript, Salesforce.com Apex and Visualforce,
 Modelica, PLSQL, Apache Velocity, XML, XSL, Scala.
 
 Additionally it includes **CPD**, the copy-paste-detector. CPD finds duplicated code in
 C/C++, C#, Dart, Fortran, Go, Groovy, Java, JavaScript, JSP, Kotlin, Lua, Matlab, Modelica,
 Objective-C, Perl, PHP, PLSQL, Python, Ruby, Salesforce.com Apex, Scala, Swift, Visualforce and XML.
 
-## Support
+In the future we hope to add support for data/control flow analysis and automatic (quick) fixes where
+it makes sense.
+
+## 🚀 Installation and Usage
+
+Download the latest binary zip from the [releases](https://github.com/pmd/pmd/releases/latest)
+and extract it somewhere.
+
+Execute `bin/run.sh pmd` or `bin\pmd.bat`.
+
+See also [Getting Started](https://pmd.github.io/latest/pmd_userdocs_installation.html)
+
+**Demo:**
+
+For this sample file:
+
+```java
+import java.util.List;
+
+public class MyClass {
+  void loop(List<String> l) {
+    for (int i = 0; i < l.size(); i++) {
+      System.out.println(l.get(i));
+    }
+  }
+}
+```
+
+Run PMD on the command line:
+
+```bash
+$ run.sh pmd -d /usr/src -R rulesets/java/quickstart.xml -f xml
+<?xml version="1.0" encoding="UTF-8"?>
+<pmd xmlns="http://pmd.sourceforge.net/report/2.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://pmd.sourceforge.net/report/2.0.0 http://pmd.sourceforge.net/report_2_0_0.xsd" version="6.37.0" timestamp="2021-08-20T15:26:35.564">
+<file name="/home/andreas/temp/pmd-test/MyClass.java">
+<violation beginline="3" endline="9" begincolumn="1" endcolumn="1" rule="NoPackage" ruleset="Code Style" class="MyClass" externalInfoUrl="https://pmd.github.io/pmd-6.37.0/pmd_rules_java_codestyle.html#nopackage" priority="3">
+All classes, interfaces, enums and annotations must belong to a named package
+</violation>
+<violation beginline="5" endline="7" begincolumn="5" endcolumn="5" rule="ForLoopCanBeForeach" ruleset="Best Practices" class="MyClass" method="loop" externalInfoUrl="https://pmd.github.io/pmd-6.37.0/pmd_rules_java_bestpractices.html#forloopcanbeforeach" priority="3">
+This for loop can be replaced by a foreach loop
+</violation>
+</file>
+</pmd>
+```
+
+PMD Eclipse Plugin:
+
+![Screenshot PMD Eclipse Plugin](docs/images/userdocs/screenshot_pmd-eclipse-plugin.png)
+
+There are plugins for Maven and Gradle as well as for various IDEs.
+See [Tools / Integrations](https://pmd.github.io/latest/pmd_userdocs_tools.html)
+
+## ℹ️ How to get support?
 
 *   How do I? -- Ask a question on [StackOverflow](https://stackoverflow.com/questions/tagged/pmd)
     or on [discussions](https://github.com/pmd/pmd/discussions).
@@ -29,7 +84,9 @@ Objective-C, Perl, PHP, PLSQL, Python, Ruby, Salesforce.com Apex, Scala, Swift,
 *   I have a quick question -- ask on our [Gitter chat](https://gitter.im/pmd/pmd).
 *   Where's your documentation? -- <https://pmd.github.io/latest/>
 
-## Source
+## 🤝 Contributing
+
+Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.
 
 Our latest source of PMD can be found on [GitHub](https://github.com/pmd/pmd). Fork us!
 
@@ -40,6 +97,10 @@ The rule designer is developed over at [pmd/pmd-designer](https://github.com/pmd
 Please see [its README](https://github.com/pmd/pmd-designer#contributing) for
 developer documentation.
 
-## Website
+## 🪙 Financial Contributors
 
-More information can be found on our [Website](https://pmd.github.io).
+Become a financial contributor and help us sustain our community. [Contribute](https://opencollective.com/pmd/contribute)
+
+## 📝 License
+
+[BSD Style](LICENSE)