Update README

README.md

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 This repository holds the code for a NodeJS/Express service that implements dynamic generation of IIIF manifests, compliant with version 2 of the Presentation API. Support for version 3 should be added in the future.
 
 The project uses `yarn` for dependency management and an `.env` file to set environment variables, an example of which can be found in `.env.example`.
+
+## Installation
+
+`GreekManifests` requires NodeJS v. >= 20 to be installed on the system, as well as `yarn` as a package manager, which can be installed globally via `npm`:
+
+```
+npm install -g yarn
+```
+
+To install the service itself, clone this repository on the target host (replace `<target_dir>` with a suitable path, or remove to install in `./greek-manifests`):
+
+```
+git clone https://git.electricmandarine.cloud/nicolo/greek-manifests <target_dir>
+```
+
+then run the following commands from the root folder:
+
+```
+yarn
+node app.mjs
+```
+
+This will start the [Express](https://expressjs.com) web server, which will remain attached to the terminal. This is suitable for testing purposes, for a production instance the Node process should be handled via a `systemd` unit or with [PM2](https://pm2.keymetrics.io), in addition to a reverse proxy like [Nginx](https://nginx.org/en/) or [Caddy](https://caddyserver.com/docs/).
+
+
+## Documentation
+
+Automatic JSDoc documentation for the codebase can be generated by running the following command from the root folder:
+
+```
+jsdoc -c jsdoc.json
+```
+
+assuming that `jsdoc` is available globally (or locally for the user). The HTML documentation will be available in `docs/`, open `docs/index.html` with a browser to view it.
+
+Here follows a basic description of the project's strcture and its main APIs.
+
+### IIIF Resources
+
+Relevant IIIF Resources are modeled as JavaScript classes in `src/iiif`, with an `IIIFResource` base class that provides a shared constructor. The classes are:
+
+- `Manifest`: represents a IIIF manifest object
+- `Canvas`: represents a IIIF canvas object
+- `Image`: represent an image annotation associated with a canvas
+- `Sequence`: a list of canvases, required by v2 of the IIIF Presentation API, it will be removed when moving to v3 (see also "[Presentation API support](#presentation-api-support)").
+
+### Services
+
+...
+
+### Routes
+
+...
+
+### Presentation API support
+
+Currently, the service only supports version 2 of the [IIIF Presentation API](https://iiif.io/api/presentation/2.0/), but support for version 3 is planned. It's possible that the manifest and canvas URIs will reflect the version number to keep both v2 and v3 functioning.