docs(component-store): clarify effect description

[LayZeeDK]

Despite its name, a ComponentStore is not necessarily tied to the lifecycle of a component. Let the description of ComponentStore#effect reflect this.

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ngrx/platform/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[x] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

The description of ComponentStore#effect states that an effect is tied to the lifecycle of a component.

What is the new behavior?

The description of ComponentStore#effect states that an effect is tied to the lifecycle of the component store.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[ngrxbot]

Preview docs changes for d96c176 at https://previews.ngrx.io/pr2997-d96c1765/