remove unnecessary disclosure of database settings

fixes !i3

//edit: rewritten history didn't have the problem anymore

README.md

@@ -2,8 +2,18 @@
 
 build using `mvn package`, execute as:
 
-```
-java -jar target/oshdb-extractor-0.1-SNAPSHOT-jar-with-dependencies.jar -i /.../ohsome-ignite.xml --input-prefix global-12345 -k "org.postgresql.Driver|jdbc:postgresql://10.11.12.21:5432/keytables-global-12345|username|password" -b minlon,minlat,maxlon,maxlat -o /.../output.oshdb --skip-large-relations
+```bash
+# change the following variables to your settings
+export REPNUM=12345
+export DBSERVER=servername
+export DBUSER=username
+export DBPASSWORD=password
+export DATABASE=keytables-global-$REPNUM
+export INPUTPREFIX=global-$REPNUM
+export IGNITECONF=/.../ohsome-ignite.xml
+export OUTFILE=/.../output.oshdb
+
+java -jar target/oshdb-extractor-0.1-SNAPSHOT-jar-with-dependencies.jar -i $IGNITECONF --input-prefix $INPUTPREFIX -k "org.postgresql.Driver|jdbc:postgresql://$DBSERVER:5432/$DATABASE|$DBUSER|$DBPASSWORD" -b minlon,minlat,maxlon,maxlat -o $OUTFILE --skip-large-relations
 ```
 
 You can get a full list of supported arguments by running `--help` on the jar file.