Ignore case on spellcheck (#463)

spellcheck ignore case, like other modules

.github/spellcheck-settings.yml

@@ -2,25 +2,27 @@ matrix:
 - name: Markdown
   expect_match: false
   apsell:
-    mode: en
+    lang: en
+    d: en_US
+    ignore-case: true
   dictionary:
     wordlists:
     - .github/wordlist.txt
     output: wordlist.dic
-    encoding: utf-8
   pipeline:
   - pyspelling.filters.markdown:
       markdown_extensions:
       - markdown.extensions.extra:
   - pyspelling.filters.html:
-      comments: true
+      comments: false
       attributes:
       - alt
       ignores:
       - ':matches(code, pre)'
-      - 'code'
-      - 'pre'
-      - 'blockquote'
+      - code
+      - pre
+      - blockquote
+      - img
   sources:
   - '*.md'
   - 'docs/*.md'