build-docs.jpl: Use substring job name check

To make this job debuggable on staging with personal job clones.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: Iad75b64dbc6cc3d215dc8379276a1b55c1a018b3
diff --git a/jenkins/build-docs.jpl b/jenkins/build-docs.jpl
index bf892d1..a2a0208 100644
--- a/jenkins/build-docs.jpl
+++ b/jenkins/build-docs.jpl
@@ -42,7 +42,7 @@
     }
   }
   node("master") {
-    if (env.JOB_NAME.equals("tf-m-build-docs-nightly")) {
+    if (env.JOB_NAME.contains("tf-m-build-docs-nightly")) {
       // Copy, then as atomically as possible replace previous docs with new.
       sh """
          cp -a /var/jenkins_home/jobs/$JOB_NAME/builds/$BUILD_NUMBER/archive/trusted-firmware-m/build/docs/reference_manual /var/jenkins_home/docs/reference_manual.new