added documentation on search with regular expressions to the German manual
added documentation on search with regular expressions to the German manual

bartsch-dev/jabref,oscargus/jabref,shitikanth/jabref,tschechlovdev/jabref,motokito/jabref,motokito/jabref,tschechlovdev/jabref,oscargus/jabref,Braunch/jabref,tobiasdiez/jabref,Braunch/jabref,tschechlovdev/jabref,Siedlerchr/jabref,JabRef/jabref,bartsch-dev/jabref,ayanai1/jabref,bartsch-dev/jabref,mairdl/jabref,zellerdev/jabref,mairdl/jabref,mredaelli/jabref,mredaelli/jabref,JabRef/jabref,Mr-DLib/jabref,mairdl/jabref,oscargus/jabref,grimes2/jabref,shitikanth/jabref,sauliusg/jabref,tschechlovdev/jabref,grimes2/jabref,oscargus/jabref,oscargus/jabref,jhshinn/jabref,sauliusg/jabref,tschechlovdev/jabref,obraliar/jabref,Mr-DLib/jabref,ayanai1/jabref,jhshinn/jabref,Mr-DLib/jabref,JabRef/jabref,shitikanth/jabref,mredaelli/jabref,shitikanth/jabref,Siedlerchr/jabref,jhshinn/jabref,tobiasdiez/jabref,jhshinn/jabref,mredaelli/jabref,obraliar/jabref,bartsch-dev/jabref,grimes2/jabref,obraliar/jabref,mredaelli/jabref,grimes2/jabref,Mr-DLib/jabref,sauliusg/jabref,ayanai1/jabref,ayanai1/jabref,motokito/jabref,grimes2/jabref,zellerdev/jabref,Siedlerchr/jabref,obraliar/jabref,motokito/jabref,obraliar/jabref,Braunch/jabref,ayanai1/jabref,Braunch/jabref,zellerdev/jabref,Braunch/jabref,tobiasdiez/jabref,tobiasdiez/jabref,bartsch-dev/jabref,zellerdev/jabref,mairdl/jabref,motokito/jabref,Mr-DLib/jabref,zellerdev/jabref,jhshinn/jabref,Siedlerchr/jabref,JabRef/jabref,shitikanth/jabref,mairdl/jabref,sauliusg/jabref