Hotfix: Only Achive build/docs in Build Docs

There is no folder named build/install/export in build docs workspace.
Achiving this folder would cause failure and block jobs.

Change-Id: I5a9c18f9843a350fdef4dfd0d7de0b3d8bf350a8
Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
diff --git a/jenkins/build-docs.jpl b/jenkins/build-docs.jpl
index 19e3a9a..38b207f 100644
--- a/jenkins/build-docs.jpl
+++ b/jenkins/build-docs.jpl
@@ -78,7 +78,6 @@
     }
     stage("Post") {
       archiveArtifacts 'trusted-firmware-m/build/docs/**'
-      archiveArtifacts 'trusted-firmware-m/build/install/export/**'
     }
   } catch (Exception e) {
     manager.buildFailure()