Update regex examples to be more durable

Change will match exactly one of options and not contains.

Update example to match a specific type and not just includes text

Author: hborham

README.md

@@ -448,7 +448,7 @@ Example synchronous message:
             "matchers": [
               {
                 "match": "regex",
-                "regex": "CONTENT_MATCHER|CONTENT_GENERATOR"
+                "regex": "^(CONTENT_MATCHER|CONTENT_GENERATOR)$"
               }
             ]
           }

testcases/message/body/matches with regex.json

@@ -30,15 +30,15 @@
           "matchers": [
             {
               "match": "regex",
-              "regex": "red|blue"
+              "regex": "^(red|blue)$"
             }
           ]
         },
         "$.alligator.favouriteColours[1]": {
           "matchers": [
             {
               "match": "regex",
-              "regex": "red|blue"
+              "regex": "^(red|blue)$"
             }
           ]
         }

testcases/request/body/matches with regex xml.json

@@ -20,7 +20,7 @@
           "matchers": [
             {
               "match": "regex",
-              "regex": "red|blue"
+              "regex": "^(red|blue)$"
             }
           ]
         }

testcases/request/body/matches with regex.json

@@ -20,15 +20,15 @@
           "matchers": [
             {
               "match": "regex",
-              "regex": "red|blue"
+              "regex": "^(red|blue)$"
             }
           ]
         },
         "$.alligator.favouriteColours[1]": {
           "matchers": [
             {
               "match": "regex",
-              "regex": "red|blue"
+              "regex": "^(red|blue)$"
             }
           ]
         }