Create a configuration.md file for each adaptor

[mtuchi]

Description

Currently we are using the configuration-schema.json to generate the sample configuration. We are checking the required list and then display a sample configuration based on the key we find in that required list. And for adaptors that do not have required property we are showing all available properties on the sample configuration schema. See this PR for more details OpenFn/docs#492

Request in few words

Create a configuration.md that will be used to document sample configuration and the full configuration-schema.
Once this is done, update OpenFn/docs to use the newly created configuration.md file instead of generating the page using sampleConfiguration() function

[josephjclark]

We don't need to do it for every adaptor - just those for whom "Show all properties" and "show all required properties" is not helpful (like http).

Basically we want the OPTION to manually define a sample configuration

[mtuchi]

For consistency and maintainability, i think we should have configuration.md for all adaptors if we decided to go with this approach