test-that.md: Fix links to crbug.com

MD wants to link to a relative URL if https:// is omitted.

TBR=akeshet@chromium.org

BUG=None
TEST=Opened in Chrome

Change-Id: I296f6feb3b2bbecf5db5f0e5b1ee3d87d1c456ff
Reviewed-on: https://chromium-review.googlesource.com/602208
Commit-Ready: Lutz Justen <ljusten@chromium.org>
Tested-by: Lutz Justen <ljusten@chromium.org>
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
diff --git a/docs/test-that.md b/docs/test-that.md
index 164ca18..14b1ae4 100644
--- a/docs/test-that.md
+++ b/docs/test-that.md
@@ -105,10 +105,10 @@
 
  - This feature will only work on builds that produced autotest test artifacts.
    If your build doesn't have such artifacts, you will see a
-   [confusing error](crbug.com/354556). The easiest way today to guarantee
-   that hwtest artifacts are produced is to make sure that your tryjob
-   is launched with the --hwtest flag. Once [this bug](crbug.com/299838) is
-   fixed that will no longer be the case.
+   [confusing error](https://crbug.com/354556). The easiest way today to
+   guarantee that hwtest artifacts are produced is to make sure that your tryjob
+   is launched with the --hwtest flag. Once [this bug](https://crbug.com/299838)
+   is fixed that will no longer be the case.
  - By default, jobs will be scheduled in the `suites` machine pool. That can be
    overridden with the `-p` flag.
  - This will only work with images newer than Sept 20, 2013 (specifically, builds