Documentation for the usage of the outbound network connections

[shadeofblue]

This task aims to prepare an initial version of a handbook article containing information about outbound network usage. It should assume that the reader doesn't know much about the outbound network per se (what does it exactly mean, where would I need this feature etc), but is already familiar with the requestor/provider model and has the essential tools (like yagna daemon) installed and running.

The article should cover the following topics:

• What is the outbound network and when would a user need it
• How golem approaches outbound network connections (with whitelists and manifests, not mentioning CA for now)
• How to prepare a manifest
• How to launch a service based on a manifest directly through yapapi
• How to prepare a dApp descriptor which uses a manifest definition
• How to verify if the outbound network is working correctly

The article about signing the manifests with CA should be covered separately, as it won't be as common practice as the outbound network usage itself

currently available documentation: https://handbook.golem.network/requestor-tutorials/service-development/service-example-6-external-api-request

The article should be prepared either as:

• a change request in the develop handbook:
  https://app.gitbook.com/o/-MBiGsNetbg_RPR_D8Hs/s/-MEXbUiNfYXXMgR7xEyA/
• or - as a pull request to the develop branch of the yagna-docs repo: https://github.com/golemfactory/yagna-docs/tree/develop

[approxit]

We need to prepare specific place for docs mentioned in this issue.

[approxit]

@VanDavv declared to scan handbook for outbound-related docs.
Also, instead of creating specific place in docs, we could just prepare the content in SDK's team notion.

[VanDavv]

The outbound network is mentioned in the following:

https://handbook.golem.network/requestor-tutorials/service-development/service-example-6-external-api-request
https://handbook.golem.network/requestor-tutorials/vm-runtime/computation-payload-manifest
https://handbook.golem.network/provider-tutorials/provider-cli#advanced-settings (briefly)