Fix "description:" field for affected jobs

Was written as "Description:" and didn't have effect.

Also, fix typos /e laborate descriptions where applicable.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I92973abdd892fc5d41e42a9ddafbd5d123544450
diff --git a/tf-a-artifacts-cleanup.yaml b/tf-a-artifacts-cleanup.yaml
index f84dbbb..5a24c46 100644
--- a/tf-a-artifacts-cleanup.yaml
+++ b/tf-a-artifacts-cleanup.yaml
@@ -5,7 +5,7 @@
     concurrent: true
     disabled: false
     defaults: global
-    Description: |
+    description: |
       Gradually cleanup artifacts in TF-A builds
     properties:
         - build-discarder: