xargs: add example as discussed in #878
xargs: add example as discussed in #878

Also moved the concrete example to the end.
cptdeka10/tldr,deekim/tldr,slash3b/tldr,UncommonPleb/tldr,Phizho/tldr,zoisom/tldr,deekim/tldr,felixonmars/tldr,zoisom/tldr,slash3b/tldr,felixonmars/tldr,AgamAgarwal/tldr,katekyan/tldr,AgamAgarwal/tldr,cptdeka10/tldr,felixonmars/tldr,katekyan/tldr,UncommonPleb/tldr,cptdeka10/tldr,zoisom/tldr,katekyan/tldr,deekim/tldr,slash3b/tldr,UncommonPleb/tldr,Phizho/tldr,Phizho/tldr