Add maintained consumer migration examples

examples/consumers/testdata/seriatim/autocorrect.yml

@@ -0,0 +1,5 @@
+rules:
+  - find: teh
+    replace: the
+  - find: occured
+    replace: occurred

examples/consumers/testdata/seriatim/speakers.yml

@@ -0,0 +1,5 @@
+rules:
+  - prefix: 'Host:'
+    name: narrator
+  - prefix: 'Guest:'
+    name: visitor

examples/consumers/testdata/seriatim/unknown-field.yml

@@ -0,0 +1,4 @@
+rules:
+  - prefix: 'Host:'
+    name: narrator
+    color: blue