docs: add warning about our current Bun setup

.github/workflows/ci.yaml

@@ -23,6 +23,11 @@ jobs:
       - name: Set up Bun
         uses: oven-sh/setup-bun@v2
         with:
+          # We're using the latest version of Bun for now, but it might be worth
+          # reconsidering. They've pushed breaking changes in patch releases
+          # that have broken our CI.
+          # Our PR where issues started to pop up: https://github.com/coder/modules/pull/383
+          # The Bun PR that broke things: https://github.com/oven-sh/bun/pull/16067
           bun-version: latest
       - name: Install dependencies
         run: bun install