update the rest-api component documentation

[khanzadyan]

After the recent release, the REST API component gained new functionality and some of the limitations are gone.

Review the documentation and make the changes.

[khanzadyan]

@stas-fomenko can you please check and let me know what needs to be changed and added in the REST API documentation which is here: https://docs.elastic.io/integrator-guide/rest-api-component

Just comment it here so that I can start working on it.

[stas-fomenko]

@khanzadyan Latest updates:

• Attachments support (https://github.com/elasticio/rest-api-component/issues/30)
• Redirects (https://github.com/elasticio/rest-api-component/issues/40)
• Improved error handling (https://github.com/elasticio/rest-api-component/issues/41)

[khanzadyan]

Thanks @stas-fomenko, I will proceed with the update using this information.

[khanzadyan]

Update on 18th of September 2019: the component document was updated https://docs.elastic.io/components/rest-api-component.html