Update CONTRIBUTING.md (#5267)
Update CONTRIBUTING.md (#5267)

Shorten the file. Remove eclipse smarthome references.

Signed-off-by: David Gräff <cddf4d21ffd604ccd3fdffe1267f1f9d72e179ea@web.de>
Snickermicker/openhab2,theoweiss/openhab2,Snickermicker/openhab2,clinique/openhab2,clinique/openhab2,Snickermicker/openhab2,clinique/openhab2,theoweiss/openhab2,theoweiss/openhab2,clinique/openhab2,Snickermicker/openhab2,theoweiss/openhab2