Clava-JS README is outdated/incomplete

[Guilherme-Soares-Sequeira]

The README is an important piece of documentation, especially for smoothing out the onboarding process of future contributors. Currently there are various missing pieces of information which are easy to add, namely:

• The package.json code provided has a trailing comma which is not supported by node at the time of writing
• The NPM development flow section could be expanded upon with, for example, the need to run npm run java-dist so that changes made in the JS side of the API are reflected in the Java version of Clava
• Node and Java version constraints are not mentioned
• Personally, I think a succinct walk-through of the directory structure, including a brief description of important directories, would greatly help new contributors

[lm-sousa]

I agree. There is a dire need for better documentation.
If you are willing/able to contribute to this effort (and I noticed you self-assigned this issue) I would gladly review the documentation changes to make sure they are accurate and complete.
Otherwise I will only be able to change this in about a month's time.