Cleanup job config text and help

Author: rmg

src/main/java/org/jenkinsci/plugins/mktmpio/MktmpioBuildWrapper.java

@@ -138,7 +138,7 @@ public boolean isApplicable(AbstractProject<?, ?> item) {
         }
 
         public String getDisplayName() {
-            return "Temporary databases by mktmpio";
+            return "Create temporary database server for build";
         }
 
         public ListBoxModel doFillInstanceTypeItems() {

src/main/resources/org/jenkinsci/plugins/mktmpio/MktmpioBuildWrapper/help-instanceType.html

@@ -1,4 +1,21 @@
 <div>
-    Type of temporary database to create.
-    Database connection and credential details will be exposed as environment variables.
+    Specify the type of temporary database to create.
+    <p>
+        Database connection and credential details will be exposed as environment variables.
+        <dl>
+            <dt>MKTMPIO_HOST</dt>
+            <dd>hostname or IP of database server</dd>
+            <dt>MKTMPIO_PORT</dt>
+            <dd>port the server is listening on</dd>
+            <dt>MKTMPIO_USERNAME</dt>
+            <dd>root-level user to use when connecting to the server, if required</dd>
+            <dt>MKTMPIO_PASSWORD</dt>
+            <dd>password for server, if required</dd>
+            <dt>MKTMPIO_ID</dt>
+            <dd>mktmpio instance id, which can be useful for debugging</dd>
+            <dt>MKTMPIO_TYPE</dt>
+            <dd>type of server that has been created</dd>
+        </dl>
+    </p>
+
 </div>