Add Heft page

_data/navigation.yaml

@@ -23,6 +23,11 @@ docs_nav:
       - title: Project roadmap
         url: /pages/overview/roadmap
 
+  - title: Heft
+    subitems:
+      - title: Overview
+        url: /pages/heft/overview
+
   - title: Contributing
     subitems:
       - title: Getting Started

pages/heft/overview.md

@@ -0,0 +1,50 @@
+---
+layout: page
+title:
+navigation_source: docs_nav
+---
+
+<img src="{{ site.baseurl }}/images/heft-300x120.png" alt="heft" title="heft" style="width: 300px;"/>
+
+🚨 *The Heft project is still in early preview. Please report any issues you encounter.* 🚨
+
+Heft is an extensible build system designed for use with the [Rush Stack](https://rushstack.io/) family of tools.
+You don't need a monorepo to use Heft, though.  It also works well for small standalone projects.  Compared to
+other similar systems, Heft has some unique design goals:
+
+- **Scalable**: Heft is designed to interface with the [Rush](https://rushjs.io) build orchestrator which is
+  optimized for large monorepos with many people and projects.  (Usage of Rush is optional.)
+
+- **Familiar**: Heft is a plain Node.js application, so developers won't need to install any native prerequisites
+  such as Python, MSYS2, or the .NET Framework.  Heft's source code is easy to understand and debug because everything
+  is 100% TypeScript, the same programming language as your web projects.  Developing for native targets is also
+  supported, of course.
+
+- **Polished and Complete**: Philosophically, Rush Stack aspires to provide a functionally complete toolkit with
+  a professional developer experience.  Pluggable task abstractions actually work against this goal:
+  It's expensive to support and optimize (and document!) every possible combination of pieces.  Also, the best
+  optimizations rely heavily on assumptions about what's behind the abstraction.  (As one example, sharing
+  compiler state with the linter requires fairly different strategies for ESLint versus TSLint.)  Heft is customizable,
+  but our focus is to invest deeply in one recommended approach that everyone can use.
+
+- **Extensible**: Most large projects require specialized additional tooling such as preprocessors, postprocessors,
+  instrumentation, and reporting.  Heft allows you to write your own plugins using the
+  [tapable](https://www.npmjs.com/package/tapable) hook system (familiar from Webpack).  Compared to loose
+  architectures such as Grunt or Gulp, Heft ships a standardized set of stages for custom tasks to hook into.
+  Working from a more standardized foundation makes custom rigs more understandable for newcomers.
+
+- **Optimized**: Heft tracks fine-grained performance metrics at each step.  Although Heft is still in its
+  early stages, it already implements optimizations such as: incremental compilation, symlinking of cache files
+  to avoid copying, reuse of compiler state across multiple emit targets, and a single compiler pass for
+  Jest and Webpack.
+
+
+## How do I use it?
+
+Heft is still under active development; more documentation will be coming soon.  In the meantime, here are
+a couple test projects that illustrate Heft setups:
+
+- [heft-test-01](https://github.com/microsoft/rushstack/tree/master/build-tests/heft-test-01): A basic Node.js
+  application with Jest and API Extractor
+- [heft-test-webpack](https://github.com/microsoft/rushstack/tree/master/build-tests/heft-test-webpack): A basic
+  web application bundled using Webpack