docs: Add twitterparser example to use lbsntransform as a package

docs/package.md

@@ -17,6 +17,19 @@ which includes the code that is invoked on command line use.
 
 We plan to update this section with a Jupyter Lab example notebook.
 
+### Example tool "twitterparser"
+
+An example program `twitterparser` that uses lbsntransform as a package is available 
+[here](https://gitlab.vgiscience.de/lbsn/tools/twitterparser).
+
+The tool demonstrates an (imaginary) custom processing pipeline for Twitter data, 
+stored in ZIP files on a remote server. The `twitterparser` tool will `(1)` connect to
+this remote server via SSH, `(2)` pull zip files and extract the json files locally and `(3)`
+transfer json files to a remote [lbsn-raw](https://gitlab.vgiscience.de/lbsn/databases/rawdb) 
+or [lbsn-hll](https://gitlab.vgiscience.de/lbsn/databases/hlldb) database using lbsntransform.
+
+Use this tool as a template or starting point and modify `__main__` to your needs.
+
 ## Contribute
 
 lbsntransform is in an early stage of development.