Add presto-docs/README.md with instructions to build Presto docs

README.md

@@ -85,6 +85,10 @@ We recommend you use IntelliJ as your IDE. The code style template for the proje
 * Use an assertion from Airlift's `Assertions` class if there is one that covers your case rather than writing the assertion by hand. Over time we may move over to more fluent assertions like AssertJ.
 * When writing a Git commit message, follow these [guidelines](https://chris.beams.io/posts/git-commit/).
 
+## Building the Documentation
+
+To learn how to build the docs, see the [docs README](presto-docs/README.md).
+
 ## Building the Web UI
 
 The Presto Web UI is composed of several React components and is written in JSX and ES6. This source code is compiled and packaged into browser-compatible Javascript, which is then checked in to the Presto source code (in the `dist` folder). You must have [Node.js](https://nodejs.org/en/download/) and [Yarn](https://yarnpkg.com/en/) installed to execute these commands. To update this folder after making changes, simply run:

presto-docs/README.md

@@ -0,0 +1,40 @@
+# Building the documentation
+
+Presto documentation is authored in `rst` format and published using [Sphinx](https://www.sphinx-doc.org). The rst files are located in `presto-docs/src/main/sphinx` and sub-folders.
+
+## Prerequisites
+
+Building the presto-docs module requires Python3 with virtual environment. You can check if you have it installed by running:
+```
+python3 -m venv --help
+```
+
+To install venv:
+```
+python3 -m pip install --user virtualenv
+```
+
+## Building manually
+The default build uses Apache Maven to download dependencies and generate the HTML. You can run it as follows:
+```
+cd presto-docs
+mvn install
+```
+Or, to build the documentation more quickly:
+```
+cd presto-docs
+./build
+```
+## Viewing the documentation
+When the build is complete, you'll find the output HTML files in the `target/html/` folder.
+
+To view the docs, you can open the file `target/html/index.html` in a web browser on macOS with
+```
+open target/html/index.html
+```
+Or, you can start a web server e.g., using Python:
+```
+cd target/html/
+python3 -m http.server
+```
+and open [http://localhost:8000](http://localhost:8000) in a web browser.