grep.md: add -l example (#913)
grep.md: add -l example (#913)


zoisom/tldr,katekyan/tldr,slash3b/tldr,Phizho/tldr,UncommonPleb/tldr,Phizho/tldr,UncommonPleb/tldr,cptdeka10/tldr,deekim/tldr,Phizho/tldr,zoisom/tldr,AgamAgarwal/tldr,zoisom/tldr,cptdeka10/tldr,AgamAgarwal/tldr,UncommonPleb/tldr,felixonmars/tldr,katekyan/tldr,slash3b/tldr,deekim/tldr,cptdeka10/tldr,slash3b/tldr,felixonmars/tldr,felixonmars/tldr,katekyan/tldr,deekim/tldr