Include flag context in excerpt (#294)

* Added avoid flag text to meta descriptions

* Moved meta description logic to a shortcode

* Fixing nunjucks syntax error in base template head

Co-authored-by: Oscar <ovlb@users.noreply.github.com>

11ty/shortcodes/__tests__/metaDescriptionWithFlag.spec.js

@@ -0,0 +1,43 @@
+import test from 'ava';
+
+import metaDescriptionWithFlag from '../metaDescriptionWithFlag';
+
+test('renders with flag.level = avoid and flag.text present', (t) => {
+  const flag = {
+    level: 'avoid',
+    text: 'ableist slur'
+  };
+  const preview = 'here is some preview text';
+
+  t.is(
+    metaDescriptionWithFlag(preview, flag),
+    'Avoid: ableist slur. Here is some preview text'
+  );
+});
+
+test('renders with flag.level = avoid and no flag.text', (t) => {
+  const flag = {
+    level: 'avoid'
+  };
+  const preview = 'here is some preview text';
+
+  t.is(
+    metaDescriptionWithFlag(preview, flag),
+    'Avoid: here is some preview text'
+  );
+});
+
+test('renders with flag.level != avoid', (t) => {
+  const flag = {
+    level: 'warning'
+  };
+  const preview = 'here is some preview text';
+
+  t.is(metaDescriptionWithFlag(preview, flag), 'Here is some preview text');
+});
+
+test('renders with no flag present', (t) => {
+  const preview = 'here is some preview text';
+
+  t.is(metaDescriptionWithFlag(preview), 'Here is some preview text');
+});