Changed conceal chars for markdown

vim/after/syntax/markdown.vim

@@ -3,11 +3,14 @@
 " source: https://gist.github.com/huytd/668fc018b019fbc49fa1c09101363397
 
 " Custom conceal
+let dtd_ignore_case=0
 syntax match todoCheckbox "\[\ \]" conceal cchar=☐
-syntax match todoCheckbox "\[[xX]\]" conceal cchar=☑
+syntax match todoCheckbox "\[X\]" conceal cchar=☒
+syntax match todoCheckbox "\[x\]" conceal cchar=☑
 
 syntax match todoCheckbox "- \[\ \]" conceal cchar=☐
-syntax match todoCheckbox "- \[[xX]\]" conceal cchar=☑
+syntax match todoCheckbox "- \[X\]" conceal cchar=☒
+syntax match todoCheckbox "- \[x\]" conceal cchar=☑
 
 hi def link todoCheckbox Todo