Update documentation

[kd-ods]

The documentation needs to be brought up-to-date to reflect current behaviour in the plugin.

On reflection, I think the documentation will remain pretty concise. We should therefore just stick with a ReadMe for now (rather than, for example, moving to multiple markdown files plus a GitHub Pages or ReadTheDocs build). Or at least, let's proceed with that premise.

TOC is something like:

• Requirements
• Overview
• Installation
• Usage
  • Create a new OFDS project
  • Create an OFDS project from existing data
  • Edit an existing OFDS JSON dataset
  • Validate your OFDS project
  • Export your project as OFDS JSON
  • Save your project as an OFDS GeoPackage
• FAQs
• Development

[duncandewhurst]

Single page sounds good to me.

Once the plugin is updated for OFDS 0.4 we should publish it to the QGIS plugin repository so hopefully the requirements and installation sections can be very brief.

For usage, I suggest that we reduce the number of subheadings to:

• Create data (including creating from scratch, or from existing data)
• Edit data
• Validate data
• Save data (including exporting as JSON and saving as GeoPackage)

[kd-ods]

I've put the draft update to the readme on a branch. Here's the draft PR where a couple of final to-dos are noted.

[kd-ods]

We're planning to merge the docs branch into @Bjwebb's working branch. Noting here that before closing this issue we need to make sure the ReadMe is edited to:

• Update the installation instructions after Add this plugin to the QGIS repository #89 is done

• Update text & links to documentation from OFDS documentation site: https://standard.ofds.info/en/0.4-dev/guidance/use/#qgis