docs(readme): create toml snippet

README.md

@@ -103,7 +103,7 @@ auto_highlight = [
 ]
 auto_install = "prompt" # true | false
 
-[[treesitter.parser_map]]
+[treesitter.parser_map]
 # You can add custom filetype to parser mappings.
 # Determine the filetype with ':lua =vim.bo[0].filetype'.
 PKGBUILD = "bash"