Update documentation throughout repo

[spwoodcock]

Replacement of #164

We currently have some minimal documentation, which could be greatly improved.
We would really welcome PRs for this 🙏

What needs to be done:

• Proof reading of current docs and correction.
• Reduce docs duplication - we currently have the same content duplicated in a few places.
• Improve general README, contributors guidelines, etc.
• Improve developer documentation with additional examples, FAQs (if you struggled setting up FMTM anywhere, feel free to document it!).
• Improve user documentation for how to use FMTM.
• Python docstrings throughout the backend, where missing (especially on routes).
• If you particularly like writing JSDoc docstrings, then it wouldn't harm having a few in the frontend too.

[vinayakhegde1]

@spwoodcock I've imrpoved the contributing guidelines please do check

[spwoodcock]

Reopening as a more general issue for contributors to help on.

It could definitely be split into sub issues based on the description though, to make it clearer what needs to be done

[manjitapandey]

Agreed, Sorry I mistakely closed it adding fixes and this issue. Not intended.

[Joshua-Tihabwangye]

hello, can i take on this isuue and complete it?

[manjitapandey]

Sure, Is there anything specific in your mind that you are thinking to add?

Otherwise, I was thinking you could also add few video tutorials on mapper's page as well. or the product tool video?

[Joshua-Tihabwangye]

1. I have read on the Field Mapper (The person who collects data) section and I think we should add in all the necessary apps by documenting there names and also providing the Links to those apps to enable the new or first time mappers to easily know the apps they are supposed to install which are compatible or which work hand in hand with FMTM.
2. For easy access and to make the FMTM easy to work with also a link to the OSM registration site is needed below that step.