Docs: Improve consistency of require-meta-* rule violation messages

lib/rules/require-meta-docs-url.js

@@ -34,7 +34,7 @@ module.exports = {
     }],
     messages: {
       mismatch: '`meta.docs.url` property must be `{{expectedUrl}}`.',
-      missing: 'Rules should export a `meta.docs.url` property.',
+      missing: '`meta.docs.url` property is missing.',
       wrongType: '`meta.docs.url` property must be a string.',
     },
   },

lib/rules/require-meta-fixable.js

@@ -22,8 +22,8 @@ module.exports = {
     },
     schema: [],
     messages: {
-      invalid: '`meta.fixable` must be either `code`, `whitespace` or `null`.',
-      missing: 'Fixable rules must export a `meta.fixable` property.',
+      invalid: '`meta.fixable` must be either `code`, `whitespace`, or `null`.',
+      missing: '`meta.fixable` must be either `code` or `whitespace` for fixable rules.',
     },
   },
 

lib/rules/require-meta-has-suggestions.js

@@ -17,8 +17,8 @@ module.exports = {
     },
     schema: [],
     messages: {
-      shouldBeSuggestable: 'Suggestable rules should specify a `meta.hasSuggestions` property with value `true`.',
-      shouldNotBeSuggestable: 'Non-suggestable rules should not specify a `meta.hasSuggestions` property with value `true`.',
+      shouldBeSuggestable: '`meta.hasSuggestions` must be `true` for suggestable rules.',
+      shouldNotBeSuggestable: '`meta.hasSuggestions` cannot be `true` for non-suggestable rules.',
     },
   },
 

lib/rules/require-meta-schema.js

@@ -28,7 +28,7 @@ module.exports = {
       },
     ],
     messages: {
-      foundOptionsUsage: 'Found usage of rule options but no options are defined in `meta.schema`.',
+      foundOptionsUsage: '`meta.schema` has no schema defined but rule has options.',
       missing: '`meta.schema` is required (use [] if rule has no schema).',
       wrongType: '`meta.schema` should be an array or object (use [] if rule has no schema).',
     },

lib/rules/require-meta-type.js

@@ -25,7 +25,7 @@ module.exports = {
     schema: [],
     messages: {
       missing: '`meta.type` is required (must be either `problem`, `suggestion`, or `layout`).',
-      unexpected: '`meta.type` must be either `problem`, `suggestion` or `layout`.',
+      unexpected: '`meta.type` must be either `problem`, `suggestion`, or `layout`.',
     },
   },