docker: update documentation for container options (#2965)
docker: update documentation for container options (#2965)

- Created a Container options section in `docker/README.md`
- Add documentation for SOCAT_LINK
- Move CROND documentation to the new section
0rax/gogs,denji/gitea_tmp,mark77z/tt2016,Spice-King/gogs,0rax/gogs,richmahn/gogs,spacetourist/gitea,cumgun/gitea,gogits/gogs,typeless/gitea,Bwko/gitea,bygreencn/gogs,andreynering/gitea,typeless/gitea,tanapoln/gogs,strk/gogs,wangjild/gogs,cgars/gogs,kubatyszko/gitea,dancewing/gogs,bkcsoft/gogs,ethantkoenig/gitea,manfer/gogs,mark77z/tt2016,linquize/gogs,chriswatt/gogs,Morlinest/gitea,denji/gitea,mjwwit/gitea,manfer/gogs,gogits/gogs,strk/gogs,0rax/gogs,makhov/gitea,dancewing/gogs,tanapoln/gogs,mukaiu/gogs,pikacloud/pikacode,kubatyszko/gitea,tszym/gogs,denji/gitea_tmp,vdbt/gitea,go-gitea/gitea,dnmgns/gitea,xaionaro/gogs,ethantkoenig/gogs,linquize/gogs,dnmgns/gitea,cgars/gogs,pikacloud/pikacode,dancewing/gogs,odinuge/gogs,cgars/gogs,liliexuan/gogs,chriswatt/gogs,dl5rcw/gitea,kubatyszko/gitea,bygreencn/gogs,sapk-fork/gitea,Spice-King/gogs,everhopingandwaiting/gogs,bkcsoft/gogs,spacetourist/gitea,liliexuan/gogs,tszym/gogs,mukaiu/gogs,andreynering/gitea,psaavedra/gogs,gigforks/gogs,tszym/gogs,cybe/gitea,richmahn/gogs,ethantkoenig/gogs,admik/gitea,mark77z/tt2016,mpindado/gogs,jorgesumle/gitea,ethantkoenig/gitea,tboerger/gitea,psolyca/gitea,DblK/gitea,sapk-fork/gitea,psolyca/gitea,sapk/gogs,xaionaro/gogs,minecrafter/gitea,denji/gitea_tmp,odinuge/gogs,dancewing/gogs,wangjild/gogs,go-gitea/gitea,kong36088/SCAUGogits,kjellkvinge/gitea,sapk/gogs,jvanderneutstulen/gogs,lafriks/gitea,typeless/gitea,avelino/gitea,jvanderneutstulen/gogs,JonasFranzDEV/gitea,sapk-fork/gitea,bkcsoft/gogs,vCaesar/gitea,cez81/gitea,gigforks/gogs,Morlinest/gitea,kjellkvinge/gitea,puffybsd/gitea,go-gitea/gitea,avelino/gitea,vCaesar/gitea,lunny/gitea,tboerger/gitea,dnmgns/gitea,everhopingandwaiting/gogs,jvanderneutstulen/gogs,dlob/gogs,Bwko/gitea,pikacloud/pikacode,cumgun/gitea,typeless/gitea,kong36088/SCAUGogits,strk/gogs,Bwko/gitea,DblK/gitea,jorgesumle/gitea,bygreencn/gogs,ForxaCoLab/forxa,dlob/gogs,willemvd/gitea,gigforks/gogs,lafriks/gitea,tanapoln/gogs,rems4e/gitea,mukaiu/gogs,cybe/gitea,everhopingandwaiting/gogs,lafriks/gitea,tboerger/gitea,ForxaCoLab/forxa,odinuge/gogs,gigforks/gogs,xaionaro/gogs,geek1011/gitea,cez81/gitea,psaavedra/gogs,dlob/gogs,mpindado/gogs,manfer/gogs,rems4e/gitea,Spice-King/gogs,wangjild/gogs,lunny/gitea,linquize/gogs,sapk-fork/gitea,kong36088/SCAUGogits,liliexuan/gogs,psaavedra/gogs,CaeruleusAqua/gitea,xormplus/gitea,cez81/gitea,mjwwit/gitea,gogits/gogs,0rax/gogs,CaeruleusAqua/gitea,chriswatt/gogs,vdbt/gitea,denji/gitea_tmp,mpindado/gogs,JonasFranzDEV/gitea,kjellkvinge/gitea,ForxaCoLab/forxa,avelino/gitea,geek1011/gitea,sapk/gogs,lunny/gitea,everhopingandwaiting/gogs,avelino/gitea