nvim: colors: yolokai: Update pandoc and yaml syntax highlighting

This improves the highlighting for files written in pandoc markdown.
It seems having the rainbow parentheses plugin active, results in
overwriting the syntax highlighting for URLs.

nvim/.config/nvim/after/ftplugin/markdown.vim

@@ -13,3 +13,7 @@ let g:pandoc#formatting#textwidth           = 79
 let g:pandoc#formatting#mode                = "hA"
 let g:pandoc#completion#bib#mode            = 'citeproc'
 let g:pandoc#syntax#codeblocks#embeds#langs = ["c", "rust", "haskell", "literatehaskell=lhaskell", "bash=sh"]
+
+" Rainbow Parentheses affects syntax highlighting for URL links. Turn it off
+" for markdown files.
+autocmd BufEnter <buffer> RainbowToggleOff

nvim/.config/nvim/colors/yolokai.vim

@@ -482,7 +482,9 @@ local highlight_groups = {
 	plantumlColonLine = {},
 
 	--[[ 4.3.33. YAML ]]
-	yamlKey = 'Label',
+	yamlKey             = 'Label',
+	yamlBlockMappingKey = { bg=black, fg=red,   style=NONE },
+	yamlPlainScalar     = { bg=black, fg=green, style=NONE },
 
 	--[[ 4.3.34. Git ]]
 	gitrebaseBreak   = 'Keyword'        ,
@@ -638,6 +640,13 @@ local highlight_groups = {
 	pandocDelimitedCodeBlockLanguage = 'Comment',
 	pandocListItemBullet             = { bg=black, fg=purple, style=NONE },
 	pandocUListItemBullet            = { bg=black, fg=purple, style=NONE },
+	pandocReferenceURL               = { bg=black, fg=pink,   style={'underline'      }},
+	pandocReferenceDefinition        = { bg=black, fg=aqua,   style={'bold'           }},
+	pandocEmphasis                   = { bg=black, fg=purple, style={'italic'         }},
+	pandocStrong                     = { bg=black, fg=purple, style={'bold'           }},
+	pandocStrongEmphasis             = { bg=black, fg=purple, style={'bold', 'italic' }},
+	pandocStrongInEmphasis           = 'pandocStrongEmphasis',
+	pandocEmphasisInStrong           = 'pandocStrongEmphasis',
 }
 
 -- We do not care about terminals which do not support 256 colors