Updating docs by deprecating environment variables.

sdk/README.md

@@ -25,12 +25,8 @@ You can customise a component using the following environment variables:
 | Environment Variable                | Type   | Required | Default                  | Possible Values          |
 |-------------------------------------|--------|-----------|--------------------------|--------------------------|
 | SMITHY\_COMPONENT\_NAME             | string | yes      | -                        | -                        |
-| SMITHY\_BACKEND\_STORE\_TYPE        | string | yes     | -                        | local, test, \*remote    |
-| SSMITHY\_BACKEND\_STORE\_DSN   | string | no    | smithy.db                | \*                        |
 | SMITHY\_LOG\_LEVEL                  | string | false     | info, debug, warn, error |
 
-For `local` development, an `SQLite` Backend Store Type will be used.
-
 `Runners` can be supplied with `RunnerConfigOption`s to customise how a component runs.
 In the following example you can see how we change the component name:
 
@@ -42,6 +38,16 @@ component.RunTarget(
 )
 ```
 
+For local development, a default `SQLite` Backend Store Type will be used. This can be customised with:
+
+```go
+component.RunTarget(
+	ctx, 
+	sampleTarget{}, 
+	component.RunnerWithStorer(//a storer),
+)
+```
+
 ### Components
 
 #### Target