chore(github/pr): mergify configuration (leanprover-community#871)

.mergify.yml

@@ -0,0 +1,98 @@
+pull_request_rules:
+  - name: automatic merge on CI success and review avigad
+    conditions:
+      - status-success=continuous-integration/travis-ci/pr
+      - "#changes-requested-reviews-by=0"
+      - base=master
+      - label=ready-to-merge
+      - approved-reviews-by=avigad
+    actions:
+      delete_head_branch: {}
+      merge:
+        method: squash
+        strict: smart
+        strict_method: merge
+  - name: automatic merge on CI success and review rwbarton
+    conditions:
+      - status-success=continuous-integration/travis-ci/pr
+      - "#changes-requested-reviews-by=0"
+      - base=master
+      - label=ready-to-merge
+      - approved-reviews-by=rwbarton
+    actions:
+      delete_head_branch: {}
+      merge:
+        method: squash
+        strict: smart
+        strict_method: merge
+  - name: automatic merge on CI success and review digama0
+    conditions:
+      - status-success=continuous-integration/travis-ci/pr
+      - "#changes-requested-reviews-by=0"
+      - base=master
+      - label=ready-to-merge
+      - approved-reviews-by=digama0
+    actions:
+      delete_head_branch: {}
+      merge:
+        method: squash
+        strict: smart
+        strict_method: merge
+  - name: automatic merge on CI success and review cipher1024
+    conditions:
+      - status-success=continuous-integration/travis-ci/pr
+      - "#changes-requested-reviews-by=0"
+      - base=master
+      - label=ready-to-merge
+      - approved-reviews-by=cipher1024
+    actions:
+      delete_head_branch: {}
+      merge:
+        method: squash
+        strict: smart
+        strict_method: merge
+  - name: automatic merge on CI success and review ChrisHughes24
+    conditions:
+      - status-success=continuous-integration/travis-ci/pr
+      - "#changes-requested-reviews-by=0"
+      - base=master
+      - label=ready-to-merge
+      - approved-reviews-by=ChrisHughes24
+    actions:
+      delete_head_branch: {}
+      merge:
+        method: squash
+        strict: smart
+        strict_method: merge
+  - name: automatic merge on CI success and review robertylewis
+    conditions:
+      - status-success=continuous-integration/travis-ci/pr
+      - "#changes-requested-reviews-by=0"
+      - base=master
+      - label=ready-to-merge
+      - approved-reviews-by=robertylewis
+    actions:
+      delete_head_branch: {}
+      merge:
+        method: squash
+        strict: smart
+        strict_method: merge
+  - name: automatic merge on CI success and review patrickmassot
+    conditions:
+      - status-success=continuous-integration/travis-ci/pr
+      - "#changes-requested-reviews-by=0"
+      - base=master
+      - label=ready-to-merge
+      - approved-reviews-by=patrickmassot
+    actions:
+      delete_head_branch: {}
+      merge:
+        method: squash
+        strict: smart
+        strict_method: merge
+  - name: remove outdated reviews
+    conditions:
+      - base=master
+    actions:
+      dismiss_reviews:
+        approved: True

README.md

@@ -1,6 +1,10 @@
 # mathlib
 
 [![Build Status](https://travis-ci.org/leanprover-community/mathlib.svg?branch=master)](https://travis-ci.org/leanprover-community/mathlib)
+[![Mergify Status][mergify-status]][mergify]
+
+[mergify]: https://mergify.io
+[mergify-status]: https://gh.mergify.io/badges/:owner/:repo.png?style=cut
 
 ## Lean standard library