fix: improve file detection

This should fix #7 and #21 Signed-off-by: Luis Davim <luis.davim@gmail.com>

Author: luisdavim

ftdetect/helm.vim

@@ -1,4 +1,13 @@
-autocmd BufRead,BufNewFile */templates/*.{yaml,yml},*/templates/*.tpl,*.gotmpl,helmfile*.{yaml,yml} set ft=helm
+function! s:isHelm()
+ let filepath = expand("%:p")
+ let filename = expand("%:t")
+ if filepath =~ '\v/(templates|charts)/.*\.(ya?ml|gotmpl|tpl|txt)$' | return 1 | en
+ if filename =~ '\v(helmfile).ya?ml' | return 1 | en
+ if !empty(findfile("Chart.yaml", expand('%:p:h').';')) | return 1 | en
+ return 0
+endfunction
+
+autocmd BufRead,BufNewFile * if s:isHelm() | set ft=helm | en
 
 " Use {{/* */}} as comments
 autocmd FileType helm setlocal commentstring={{/*\ %s\ */}}