update some comments in preview lib
update some comments in preview lib

owncloud/core,sharidas/core,lrytz/core,bluelml/core,pixelipo/server,nextcloud/server,andreas-p/nextcloud-server,pixelipo/server,endsguy/server,owncloud/core,IljaN/core,whitekiba/server,lrytz/core,endsguy/server,andreas-p/nextcloud-server,cernbox/core,pixelipo/server,whitekiba/server,pixelipo/server,owncloud/core,Ardinis/server,xx621998xx/server,cernbox/core,pmattern/server,andreas-p/nextcloud-server,jbicha/server,bluelml/core,nextcloud/server,endsguy/server,endsguy/server,nextcloud/server,IljaN/core,pollopolea/core,pollopolea/core,bluelml/core,bluelml/core,xx621998xx/server,IljaN/core,Ardinis/server,pollopolea/core,nextcloud/server,pollopolea/core,endsguy/server,phil-davis/core,pollopolea/core,jbicha/server,pmattern/server,pmattern/server,cernbox/core,Ardinis/server,whitekiba/server,pmattern/server,owncloud/core,andreas-p/nextcloud-server,michaelletzgus/nextcloud-server,pmattern/server,jbicha/server,jbicha/server,andreas-p/nextcloud-server,michaelletzgus/nextcloud-server,Ardinis/server,cernbox/core,lrytz/core,whitekiba/server,Ardinis/server,IljaN/core,bluelml/core,xx621998xx/server,IljaN/core,lrytz/core,cernbox/core,sharidas/core,jbicha/server,xx621998xx/server,sharidas/core,whitekiba/server,michaelletzgus/nextcloud-server,sharidas/core,michaelletzgus/nextcloud-server,owncloud/core,pixelipo/server,sharidas/core,lrytz/core,xx621998xx/server