Add support for `djangohtml` (1 line change)

[savchenko]

Could you please add subj? Here:

https://github.com/tpope/vim-endwise/blob/3719ffddb5e42bf67b55b2183d7a6fb8d3e5a2b8/plugin/endwise.vim#L78

P.S. I was about to submit pull request, but contributing guidelines explicitly suggest proposing it in an issue before drafting a patch.