add CODEOWNERS, automatically manage waiting-for-author/review labels

.github/CODEOWNERS

@@ -0,0 +1 @@
+*       @rust-lang/docs-rs

.github/workflows/on-pr-review-approve.yml

@@ -0,0 +1,14 @@
+on:
+  pull_request_review:
+    types: [submitted]
+
+jobs:
+  update-labels:
+    if: github.event.review.state == 'approved'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions-ecosystem/action-remove-labels@v1
+        with:
+          labels: |
+            S-waiting-on-author
+            S-waiting-on-review

.github/workflows/on-pr-review-submit.yml

@@ -0,0 +1,15 @@
+on:
+  pull_request_review:
+    types: [submitted]
+
+jobs:
+  update-labels:
+    if: github.event.review.state == 'changes_requested'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions-ecosystem/action-add-labels@v1
+        with:
+          labels: S-waiting-on-author
+      - uses: actions-ecosystem/action-remove-labels@v1
+        with:
+          labels: S-waiting-on-review

.github/workflows/tag-new-pr.yml

@@ -2,7 +2,7 @@ on:
   pull_request_target:
     branches:
       - master
-    types: [opened, reopened]
+    types: [opened, reopened, review_requested]
 
 jobs:
   update-labels:
@@ -11,3 +11,6 @@ jobs:
       - uses: actions-ecosystem/action-add-labels@v1
         with:
           labels: S-waiting-on-review
+      - uses: actions-ecosystem/action-remove-labels@v1
+        with:
+          labels: S-waiting-on-author