chore(docs): monorepos support

docs/docs/reference/cloud/monorepos.md

@@ -0,0 +1,43 @@
+---
+title: "Monorepos"
+description: "Monorepos support in Gatsby Cloud"
+---
+
+## Introduction
+
+Gatsby Cloud has support for projects organized as [monorepos](https://monorepo.tools/), but since there are different competing tools to build a monorepo it's important to know what Gatsby Cloud supports today.
+
+This document will explain which tools are supported and how you can troubleshoot issues.
+
+## Supported tools
+
+The following table shows the level of support for each tool.
+
+**Legend:**
+
+| Icon | Feature Capability                       |
+| ---- | ---------------------------------------- |
+| ●    | Fully Supported                          |
+| ◐    | Somewhat Supported (support is minimal ) |
+| ○    | Not Supported                            |
+
+**Support:**
+
+| Tool.                            | Level of Support | Notes                                                   |
+| -------------------------------- | ---------------- | ------------------------------------------------------- |
+| Yarn Workspaces (v1)             | ●                |                                                         |
+| Yarn Workspaces (v2/v3 with PnP) | ◐                |                                                         |
+| Lerna                            | ●                |                                                         |
+| NPM Workspaces (v7 and onwards)  | ●                |                                                         |
+| NX                               | ○                | Work in progress                                        |
+| Turborepo                        | ○                | We do not have plans to support Turborepo at this time. |
+
+## Troubleshooting
+
+### PnP and Yarn compatibility issues
+
+Some tools don't work under Plug'n'Play environments, check the Yarn [compatibility table](https://yarnpkg.com/features/pnp#compatibility-table). You can enable the built-in `node-modules` plugin by adding the following into your local `.yarnrc.yml` file before running a fresh `yarn install`:
+
+```yml
+nodeLinker: node-modules
+```