Add linting pre-commit config

This uses the pre-commit project, instructions for whose installation
are coming for the README soon.

.pre-commit-config.yaml

@@ -0,0 +1,25 @@
+repos:
+  - repo: local
+    hooks:
+      - id: lint-js
+        name: "lint typescript and javascript"
+        entry: /usr/bin/env npx eslint
+        files: '\.jsx?$|\.tsx?$'
+        language: script
+        description: "Checks JS/TS code according to the package's linter configuration"
+  - repo: local
+    hooks:
+      - id: lint-config
+        name: "lint config files"
+        entry: /usr/bin/env npx prettier -c
+        files: '\.json$|\.yaml$|\.toml$'
+        language: script
+        description: "Checks config files according to the package's linter configuration"
+  - repo: local
+    hooks:
+      - id: lint-docs
+        name: "lint documentation files"
+        entry: /usr/bin/env npx prettier -c
+        files: '\.md$'
+        language: script
+        description: "Checks documentation files according to the package's linter configuration"