tree.md: add more useful examples
tree.md: add more useful examples

and reorder entries by increasing complexity

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