nvim: fix markdown fenced languages and add support for hugo front matter

config/nvim/after/syntax/markdown.vim

@@ -0,0 +1,39 @@
+" Vim syntax file                                                                                                                                                                                                                             
+" Language: markdown with embedded yaml, toml for Hugo
+" Author:   James Wright (james@jameswright.xyz)
+" License:  MIT
+" Inspired by https://github.com/pbrisbin/vim-syntax-shakespeare/blob/master/after/syntax/haskell.vim
+
+" store and remove current syntax value
+if exists('b:current_syntax')
+  let old_syntax = b:current_syntax
+  unlet b:current_syntax
+endif
+
+syn include @yaml syntax/yaml.vim
+unlet b:current_syntax
+
+syn include @toml syntax/toml.vim
+unlet b:current_syntax
+
+if getline(1) =~ '---'
+    syn region yamlBlock matchgroup=quasiQuote start=/\%^---/ end=/^---/ contains=@yaml
+elseif getline(1) =~ '+++'
+    syn region tomlBlock matchgroup=quasiQuote start=/\%^+++/ end=/^+++/ contains=@toml
+endif
+
+if version < 508
+  command! -nargs=+ HiLink hi link <args>
+else
+  command! -nargs=+ HiLink hi def link <args>
+endif
+
+
+HiLink quasiQuote     Boolean
+
+delcommand HiLink
+
+" restore current syntax value
+if exists('old_syntax')
+  let b:current_syntax = old_syntax
+endif