tomb: edit page to conform to tldr guidelines
tomb: edit page to conform to tldr guidelines

also improve example descriptions to better match the documentation in https://www.dyne.org/software/tomb and http://tomb.dyne.org/tomb_manpage.pdf
slash3b/tldr,felixonmars/tldr,UncommonPleb/tldr,zoisom/tldr,katekyan/tldr,deekim/tldr,slash3b/tldr,cptdeka10/tldr,UncommonPleb/tldr,felixonmars/tldr,Phizho/tldr,Phizho/tldr,deekim/tldr,deekim/tldr,Phizho/tldr,katekyan/tldr,slash3b/tldr,zoisom/tldr,zoisom/tldr,cptdeka10/tldr,felixonmars/tldr,UncommonPleb/tldr,katekyan/tldr,cptdeka10/tldr