Add markdown grammar

Fixes #215

runtime/queries/markdown/highlights.scm

@@ -0,0 +1,35 @@
+[
+  (atx_heading)
+  (setext_heading)
+] @markup.heading
+
+(code_fence_content) @none
+
+[
+  (indented_code_block)
+  (fenced_code_block)
+] @markup.raw.block
+
+(code_span) @markup.raw.inline
+
+(emphasis) @markup.italic
+
+(strong_emphasis) @markup.bold
+
+(link_destination) @markup.underline.link
+
+; (link_label) @markup.label ; TODO: rename
+
+[
+  (list_marker_plus)
+  (list_marker_minus)
+  (list_marker_star)
+  (list_marker_dot)
+  (list_marker_parenthesis)
+] @punctuation.special
+
+[
+  (backslash_escape)
+  (hard_line_break)
+] @string.character.escape
+

runtime/queries/svelte/highlights.scm

@@ -25,7 +25,7 @@
 
 ((attribute
    (attribute_name) @_attr
-   (quoted_attribute_value (attribute_value) @markup.undeline.link))
+   (quoted_attribute_value (attribute_value) @markup.underline.link))
  (#match? @_attr "^(href|src)$"))
 
 (tag_name) @tag