github: add labeler action (#1196)

Bit easier to do this as everything seems to be sorted into logical
folders. You may need to add new labels to support this however.

.github/labeler.yml

@@ -0,0 +1,53 @@
+# https://github.com/actions/labeler
+
+documentation:
+    - changed-files:
+        - any-glob-to-any-file:
+            - README.md
+            - LICENSE
+            - CONTRIBUTING.md
+            - libc/README.md
+            - tool/cosmocc/README.md
+            - third_party/getopt/README.txt
+testing:
+    - changed-files:
+        - any-glob-to-any-file:
+            - test/**
+build:
+    - changed-files:
+        - any-glob-to-any-file:
+            - build/**
+            - Makefile
+            - '*/*.mk'
+examples:
+    - changed-files:
+        - any-glob-to-any-file: examples/**
+devops:
+    - changed-files:
+        - any-glob-to-any-file:
+            - .github/**
+            - .clang-format
+dsp:
+    - changed-files:
+        - any-glob-to-any-file:
+            - dsp/**
+ape:
+    - changed-files:
+        - any-glob-to-any-file:
+            - ape/**
+libc:
+    - changed-files:
+        - any-glob-to-any-file:
+            - libc/**
+net:
+    - changed-files:
+        - any-glob-to-any-file:
+            - net/**
+third_party:
+    - changed-files:
+        - any-glob-to-any-file:
+            - third_party/**
+tool:
+    - changed-files:
+        - any-glob-to-any-file:
+            - tool/**

.github/workflows/labeler.yml

@@ -0,0 +1,17 @@
+name: "Pull Request Labeler"
+on:
+- pull_request_target
+
+jobs:
+  labeler:
+    permissions:
+      contents: read
+      pull-requests: write
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        repository: "jart/cosmopolitan"
+    - uses: actions/labeler@v5
+      with:
+        configuration-path: '.github/labeler.yml'