Rename our base job

Rename to add "-base" to the base job to follow Zuul conventions, also
add abstract to mark that this cannot run on its own and needs to be
inherited from.

Change-Id: Ic2228244e787395be1c5dc77a92e2ff352d47106

.zuul.yaml

@@ -4,7 +4,8 @@
 # repositories.
 
 - job:
-    name: build-tox-manuals
+    name: build-tox-manuals-base
+    abstract: true
     description: |
       Base job to build manual related documents. These build jobs
       invoke a tox command and expect the published content to be in
@@ -29,15 +30,15 @@
 
 - job:
     name: build-tox-manuals-checkbuild
-    parent: build-tox-manuals
+    parent: build-tox-manuals-base
     description: |
       Build manuals using "checkbuild" tox environment.
     vars:
       tox_envlist: checkbuild
 
 - job:
     name: build-tox-manuals-checklang
-    parent: build-tox-manuals
+    parent: build-tox-manuals-base
     description: |
       Build translated manuals using "checklang" tox environment.
     vars: