Add observability enabling instructions to specific observability tool guides

[Dilhasha]

Description

When users bring their own projects and start following the observability guides to setup specific tools, they tend to miss the instruction to enable observability for the project. So it's better to add it to each tool guide as a step.

The following instruction need to be added to all the supported observability tools documentation.

Enable observability for a Ballerina project
Observability can be enabled in a Ballerina project by adding the following section to the Ballerina.toml file.

[build-options]
observabilityIncluded=true

Steps to Reproduce

When users bring their own projects and start following the observability guides to setup specific tools, they tend to miss the instruction to enable observability for the project. So it's better to add it to each tool guide as a step.

Version

2201.13.x

Environment Details (with versions)

No response