fix(#57): address round-2 Copilot review (doc + test polish)

Author: johanrd

docs/rules/template-require-iframe-title.md

@@ -32,6 +32,8 @@ This rule **forbids** the following:
   <iframe title='   ' />
   <iframe title={{null}} />
   <iframe title={{undefined}} />
+  <iframe title={{true}} />
+  <iframe title={{false}} />
   <iframe title={{42}} />
 </template>
 ```

lib/rules/template-require-iframe-title.js

@@ -65,7 +65,7 @@ module.exports = {
       missingTitle: '<iframe> elements must have a unique title property.',
       emptyTitle: '<iframe> elements must have a unique title property.',
       invalidTitleLiteral:
-        '<iframe title> must be a non-empty string. Got a {{literalType}} literal, which does not describe the frame contents.',
+        '<iframe title> must be a non-empty string. Got {{literalType}} literal, which does not describe the frame contents.',
       duplicateTitleFirst: 'This title is not unique. #{{index}}',
       duplicateTitleOther:
         '<iframe> elements must have a unique title property. Value title="{{title}}" already used for different iframe. #{{index}}',

tests/lib/rules/template-require-iframe-title.js

@@ -232,7 +232,7 @@ hbsRuleTester.run('template-require-iframe-title', rule, {
       errors: [
         {
           message:
-            '<iframe title> must be a non-empty string. Got a boolean literal, which does not describe the frame contents.',
+            '<iframe title> must be a non-empty string. Got boolean literal, which does not describe the frame contents.',
         },
       ],
     },
@@ -242,7 +242,7 @@ hbsRuleTester.run('template-require-iframe-title', rule, {
       errors: [
         {
           message:
-            '<iframe title> must be a non-empty string. Got a boolean literal, which does not describe the frame contents.',
+            '<iframe title> must be a non-empty string. Got boolean literal, which does not describe the frame contents.',
         },
       ],
     },
@@ -260,7 +260,7 @@ hbsRuleTester.run('template-require-iframe-title', rule, {
       errors: [
         {
           message:
-            '<iframe title> must be a non-empty string. Got a boolean literal, which does not describe the frame contents.',
+            '<iframe title> must be a non-empty string. Got boolean literal, which does not describe the frame contents.',
         },
       ],
     },
@@ -270,7 +270,7 @@ hbsRuleTester.run('template-require-iframe-title', rule, {
       errors: [
         {
           message:
-            '<iframe title> must be a non-empty string. Got a null literal, which does not describe the frame contents.',
+            '<iframe title> must be a non-empty string. Got null literal, which does not describe the frame contents.',
         },
       ],
     },
@@ -280,7 +280,7 @@ hbsRuleTester.run('template-require-iframe-title', rule, {
       errors: [
         {
           message:
-            '<iframe title> must be a non-empty string. Got a undefined literal, which does not describe the frame contents.',
+            '<iframe title> must be a non-empty string. Got undefined literal, which does not describe the frame contents.',
         },
       ],
     },
@@ -290,7 +290,7 @@ hbsRuleTester.run('template-require-iframe-title', rule, {
       errors: [
         {
           message:
-            '<iframe title> must be a non-empty string. Got a number literal, which does not describe the frame contents.',
+            '<iframe title> must be a non-empty string. Got number literal, which does not describe the frame contents.',
         },
       ],
     },