Fix yamllint issues

The yamllint config file was incorrect, which meant that several
issues were not flagged properly.

.pyspelling.yml

@@ -1,23 +1,23 @@
 spellchecker: aspell
 
 matrix:
-- name: markdown
-  default_encoding: utf-8
-  sources:
-    - "**/*.md"
-  pipeline:
-    - pyspelling.filters.markdown:
-      markdown_extensions:
-      - markdown.extensions.extra:
-    - pyspelling.filters.html:
-        comments: true
-        ignores:
-          - code
-          - pre
-    - pyspelling.filters.url:
-  aspell:
-    lang: en
-  dictionary:
-    encoding: utf-8
-    wordlists:
-    - .aspell.en.pws
+  - name: markdown
+    default_encoding: utf-8
+    sources:
+      - "**/*.md"
+    pipeline:
+      - pyspelling.filters.markdown:
+        markdown_extensions:
+          - markdown.extensions.extra:
+      - pyspelling.filters.html:
+          comments: true
+          ignores:
+            - code
+            - pre
+      - pyspelling.filters.url:
+    aspell:
+      lang: en
+    dictionary:
+      encoding: utf-8
+      wordlists:
+        - .aspell.en.pws

.yamllint

@@ -1,2 +1,6 @@
-document-start: disable
-line-length: disable
+extends: default
+
+rules:
+  document-start: disable
+  line-length: disable
+  truthy: disable

tests/bug237.yaml

@@ -1,6 +1,4 @@
-
 payee_split:
   - (?<payee>.*)
 
 narration_tag: thing
-