fix typo in xsel.md
fix typo in xsel.md
katekyan/tldr,katekyan/tldr,slash3b/tldr,slash3b/tldr,UncommonPleb/tldr,Phizho/tldr,deekim/tldr,zoisom/tldr,cptdeka10/tldr,cptdeka10/tldr,deekim/tldr,AgamAgarwal/tldr,UncommonPleb/tldr,deekim/tldr,AgamAgarwal/tldr,felixonmars/tldr,felixonmars/tldr,katekyan/tldr,Phizho/tldr,UncommonPleb/tldr,Phizho/tldr,slash3b/tldr,felixonmars/tldr,zoisom/tldr,zoisom/tldr,cptdeka10/tldr