Tidy up README and add subcommand instructions

[itsspriyansh]

This PR

• adds information about available subcommands and dotcommands in README.md.
• Adds Information about standalone setup in README.md.
• Moves the app and web testing docs to separate files.

[garg3133]

@itsspriyansh We'd need to reduce the README to only the most important information and move all the detailed information to separate pages. Otherwise, someone exploring this project would never reach the part you've implemented through the readme.

See #30 for reference.

[itsspriyansh]

@garg3133 PR updated. How does it look now?

[garg3133]

@itsspriyansh Not what I meant. What I meant was to move the detailed usage sections of setting up Android/iOS requirements to separate files (as was attempted in #30 but then the author abandoned the PR) so that the README is freed up and only contains the important details.

The amount of information that you added earlier in README related to your work seemed alright, we should have some basic usage about each subcommand in the main readme itself and then move the rest to corresponding files.

[itsspriyansh]

@garg3133 PR updated

[garg3133]

The README looks good now.

[garg3133]

What's left now is to link the specific subcommand docs with the appropriate sections in README and update the subcommand files for the recently merged scripts.