Automatically label pull requests based on the file paths modified (#1273)

* Automatically label pull requests based on the file paths modified

* Add `wasmtime:c-api` labels for changes to `crates/c-api/*`

.github/labeler.yml

@@ -0,0 +1,42 @@
+# This file configures which paths automatically get which label on new pull
+# requests.
+#
+# It generally has the syntax:
+#
+#     <label 0>:
+#       - <glob-path 0>
+#       - ...
+#       - <glob-path n>
+#     ...
+#     <label n>:
+#       - <glob-path 0>
+#       - ...
+#       - <glob-path n>
+#
+# See https://github.com/actions/labeler for details.
+#
+# Note that we keep the labels in alphabetical order below.
+
+cranelift:
+  - cranelift/*
+
+"cranelift:docs":
+  - cranelift/docs/*
+
+"cranelift:meta":
+  - cranelift/codegen/meta/*
+
+lightbeam:
+  - crates/lightbeam/*
+
+fuzzing:
+  - crates/fuzzing/*
+
+wasi:
+  - crates/wasi/*
+
+"wasmtime:api":
+  - crates/api/*
+
+"wasmtime:c-api":
+  - crates/c-api/*

.github/workflows/labeler.yml

@@ -0,0 +1,11 @@
+name: "Pull Request Labeler"
+on:
+- pull_request
+
+jobs:
+  triage:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/labeler@v2
+      with:
+        repo-token: "${{ secrets.GITHUB_TOKEN }}"