Add Node version update process (#868)

Author: lognaturel

README.md

@@ -1,5 +1,4 @@
-ODK Central
-===========
+# ODK Central
 
 ![Platform](https://img.shields.io/badge/platform-Docker-blue.svg)
 [![License](https://img.shields.io/badge/license-Apache_2.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)
@@ -16,32 +15,36 @@ This repository serves as an umbrella for the Central project as a whole:
 
 If you are looking for help, please take a look at the [Documentation Website](https://docs.getodk.org/central-intro/). If that doesn't solve your problem, please head over to the [ODK Forum](https://forum.getodk.org) and do a search to see if anybody else has had the same problem. If you've identified a new problem or have a feature request, please post on the forum. We prefer forum posts to GitHub issues because more of the community is on the forum.
 
-Contributing
-------------
+## Contributing
 
 We would love your contributions to Central. If you have thoughts or suggestions, please share them with us on the [Ideas board](https://forum.getodk.org/c/ideas) on the ODK Forum. If you wish to contribute code, you have the option of working on the Backend server ([contribution guide](https://github.com/getodk/central-backend/blob/master/CONTRIBUTING.md)), the Frontend website ([contribution guide](https://github.com/getodk/central-frontend/blob/master/CONTRIBUTING.md)), or both. To set up a development environment, first follow the [Backend instructions](https://github.com/getodk/central-backend#setting-up-a-development-environment) and then optionally the [Frontend instructions](https://github.com/getodk/central-frontend#setting-up-your-development-environment).
 
+### Branches
+
 The `master` branch of this repository is a stable branch that users clone when they install Central in production. The `next` branch reflects ongoing development for the next version of Central. Note that this differs from the `central-backend` and `central-frontend` repositories, where `master` is the development branch. If you create a PR to this repository, please target the `next` branch unless you are only changing documentation like the readme.
 
+### Services
+
 In addition to the Backend and the Frontend, Central deploys services:
 
 * Central relies on [pyxform-http](https://github.com/getodk/pyxform-http) for converting Forms from XLSForm. It generally shouldn't be needed in development but can be run locally.
 * Central relies on [Enketo](https://github.com/enketo/enketo-express) for Web Form functionality. Enketo can be run locally and configured to work with Frontend and Backend in development by following [these instructions](https://github.com/getodk/central-frontend/blob/master/docs/enketo.md).
 
-If you want to work on Central codebase and don't want to setup dependent services like Postgresql, Enketo, etc manually then you can run `make dev`, which will start those services as Docker containers. With this setup you would need a local domain name, `central-dev` is a good choice. Following are the places where you need to add this:
+If you want to work on the Central codebase and don't want to setup dependent services like Postgresql, Enketo, etc manually then you can run `make dev`, which will start those services as Docker containers. This setup requires a local domain name, `central-dev` is a good choice. Add this name in the following places:
 
-* Set `DOMAIN=central-dev` in .env file. 
+* Set `DOMAIN=central-dev` in the `.env` file. 
 * Add an entry in your `/etc/hosts` file for `127.0.0.1 central-dev`.
-* Create `local.json` in central-backend directory and set value of default.env.domain to `http://central-dev:8989`
-
-Operations
-----------
+* Create `local.json` in the central-backend directory and set the value of `default.env.domain` to `http://central-dev:8989`
 
+## Operations
 This repository serves administrative functions, but it also contains the Docker code for building and running a production Central stack.
 
 To learn how to run such a stack in production, please take a look at [our DigitalOcean installation guide](https://docs.getodk.org/central-install-digital-ocean/).
 
-License
--------
+## Node.js version
+
+We aim to use the latest [active LTS version of Node.js](https://github.com/nodejs/release/blob/main/README.md#release-schedule). This means that we generally update the major Node version used across all Central components once a year. Each time we do a Central release, we update to the latest version within the active LTS line. Node updates are done near the end of the release cycle but before regression testing.
+
+## License
 
 All of ODK Central is licensed under the [Apache 2.0](https://raw.githubusercontent.com/getodk/central/master/LICENSE) License.