tcServer customization under STS

I've followed these instructions to enable a JDBC Datasource under tcServer. (Although it seems I also require the context.xml configuration described here.)

While I'm still working out the kinks in my configuration, SSHtunnel, DataSource name, etc., my particular question here is why my changes to those two files keep being overwritten and how to prevent that from occurring. That is, after adding the appropriate clauses to server.xml and context.xml, I may get one or two server restarts before those files are altered back to their original states.

I'm on STS 2.6.1, and the files I'm editing (the only ones I've found) are under
c:\springsource\tc-server-developer-2.1.1.RELEASE\spring-insight-instance\conf

Do I need to create a new instance?

In case it matters, here's what I'm adding to context.xml

Code:

---

<ResourceLink name="Contact" global="jdbc/Contact" type="javax.sql.DataSource"/>

---

And to server.xml

Code:

---

<Resource name="jdbc/ContactAZ"
              auth="Container"
              type="javax.sql.DataSource"
              username="user"
              password="password"
              driverClassName="com.ibm.db2.jcc.DB2Driver"
              url="jdbc:db2://localhost:60000/contact"/>

---

(DB2 driver jar is copied to Tomcat lib directory, and this code is being used until it's automatically removed from the config files.)

Ahhh, found it here. Looked for configuration items under the server properties, but didn't realize to look for the "Servers" *Project*.