Babylon building document correction

[nadeesh t v]

Hello,
I  was trying to build the babylon project by reading the following doc
<https://github.com/openjdk/babylon/blob/code-reflection/hat/docs/hat-01-02-building-babylon.md>
and
noticed a minor correction and attached a patch for it.
For the 2nd change related to clearing JTREG, without that I was running
into the below error.
```

treg/build/images/jtreg/ is not a valid keyword for JTREG.

Valid keywords: JOBS TIMEOUT_FACTOR FAILURE_HANDLER_TIMEOUT TEST_MODE
ASSERT VERBOSE RETAIN TEST_THREAD_FACTORY JVMTI_STRESS_AGENT MAX_MEM
RUN_PROBLEM_LISTS RETRY_COUNT REPEAT_COUNT MAX_OUTPUT REPORT AOT_JDK MANUAL
OPTIONS JAVA_OPTIONS VM_OPTIONS KEYWORDS EXTRA_PROBLEM_LISTS
LAUNCHER_OPTIONS.

RunTests.gmk:205: *** Cannot continue.  Stop.

make[2]: *** [test] Error 2

```

Not sure it is a *my* issue , rather than a generic issue. Let me know
whether it's worth  making a PR for this.
-- 
Thanks and Regards,
Nadeesh
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mail.openjdk.org/pipermail/babylon-dev/attachments/20251128/0ccec009/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: buildDoc.patch
Type: application/x-patch
Size: 641 bytes
Desc: not available
URL: <https://mail.openjdk.org/pipermail/babylon-dev/attachments/20251128/0ccec009/buildDoc.patch>