👷 Rename and clarify CI workflow job names (#3570)

.github/workflows/build-docs.yml

@@ -4,7 +4,7 @@ on:
   pull_request:
     types: [opened, synchronize]
 jobs:
-  build:
+  build-docs:
     runs-on: ubuntu-18.04
     steps:
       - name: Dump GitHub context

.github/workflows/preview-docs.yml

@@ -7,7 +7,7 @@ on:
       - completed
 
 jobs:
-  deploy:
+  preview-docs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2