Issue #3495141: Creates rule field.

Closes #3495141

config/schema/alt_text_validation.schema.yml

@@ -36,3 +36,38 @@ alt_text_validation_audit:
     file_source:
       type: string
       label: 'File source location'
+
+# The Alt-Text Rule Configuration Entity
+alt_text_validation.alt_text_rule.*:
+  type: config_entity
+  label: 'Alt-Text Rule'
+  mapping:
+    id:
+      type: string
+      label: 'ID'
+      translatable: false
+    label:
+      type: label
+      label: 'Label'
+      translatable: true
+    rule_type:
+      type: string
+      label: 'Rule Type'
+      translatable: false
+    content_char_limit:
+      type: integer
+      label: 'Content Character Limit'
+      translatable: false
+    text_to_compare:
+      type: text
+      label: 'Text to Compare'
+      translatable: true
+    violation_action:
+      type: string
+      label: 'Violation Action'
+      translatable: false
+    violation_message:
+      type: text
+      label: 'Violation Message'
+      translatable: true
+