docs: boundaries experimental page (#9834)

### Description

Documenting the experimental release of Boundaries built-ins.

### Testing Instructions

👀

Author: anthonyshew

docs/repo-docs/reference/boundaries.mdx

@@ -0,0 +1,27 @@
+---
+title: boundaries
+description: API reference for the `turbo boundaries` command
+---
+
+import { ExperimentalBadge } from '#/components/experimental-badge';
+import { Callout } from '#/components/callout';
+
+<ExperimentalBadge>Experimental</ExperimentalBadge>
+
+Boundaries ensure that Turborepo features work correctly by checking for package manager Workspace violations.
+
+```bash title="Terminal"
+turbo boundaries
+```
+
+This command will notify for two types of violations:
+
+- Importing a file outside of the package's directory
+- Importing a package that is not specified as a dependency in the package's `package.json`
+
+<Callout title="Boundaries RFC">
+  This feature is experimental, and we're looking for your feedback on [the
+  Boundaries RFC](https://github.com/vercel/turborepo/discussions/9435).
+  Additionally, please provide your use cases for user-defined Boundaries to
+  help inform the next iteration of our design.
+</Callout>

docs/repo-docs/reference/index.mdx

@@ -45,11 +45,21 @@ Turborepo's API reference is broken up into the following sections:
         description="Run tasks using `turbo`."
     />
 
+    <Card
+        title="watch"
+        href="/repo/docs/reference/watch"
+        description="Dependency-aware, single-process task watcher."
+    />
     <Card
         title="prune"
         href="/repo/docs/reference/prune"
         description="Create partial monorepos for target workspaces."
     />
+    <Card
+        title="boundaries"
+        href="/repo/docs/reference/boundaries"
+        description="Enforce best practices in your monorepo."
+    />
     <Card
         title="ls"
         href="/repo/docs/reference/ls"

docs/repo-docs/reference/meta.json

@@ -11,6 +11,7 @@
     "run",
     "watch",
     "prune",
+    "boundaries",
     "ls",
     "query",
     "generate",