Spellcheck (#302)

* spelling, take1

* some spelling fixes

* one more

.github/spellcheck-settings.yml

@@ -0,0 +1,26 @@
+matrix:
+- name: Markdown
+  expect_match: false
+  apsell:
+    mode: en
+  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
+      attributes:
+      - alt
+      ignores:
+      - ':matches(code, pre)'
+      - 'code'
+      - 'pre'
+      - 'blockquote'
+  sources:
+  - '*.md'
+  - 'docs/*.md'