Update the README to match other scripting plugins

Author: ctrueden

README.md

@@ -2,4 +2,21 @@
 
 # Python Scripting
 
-Test repository for a [PyImageJ](https://github.com/imagej/pyimagej) based SciJava scripting language engine.
+This library provides a
+[JSR-223-compliant](https://en.wikipedia.org/wiki/Scripting_for_the_Java_Platform)
+scripting plugin for the [Python](https://python.org/) language, built on
+the [scyjava](https://github.com/scijava/scyjava) Python package.
+
+It is implemented as a `ScriptLanguage` plugin for the [SciJava
+Common](https://github.com/scijava/scijava-common) platform, which means that
+in addition to being usable directly as a `javax.script.ScriptEngineFactory`,
+it also provides some functionality on top, such as the ability to generate
+lines of script code based on SciJava events.
+
+For a complete list of scripting languages available as part of the SciJava
+platform, see the
+[Scripting](https://github.com/scijava/scijava-common/wiki/Scripting) page on
+the SciJava Common wiki.
+
+See also:
+* [Python Scripting](https://imagej.net/scripting/python) on the ImageJ wiki.