docs(effects): update examples to standalone api

[AdrianRomanski]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ngrx/platform/blob/main/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?

Closes #4468

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

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[timdeschryver]

Thanks for your work on this @AdrianRomanski
For next time, also try to add the issue number into the PR template (I've updated it now)

[AdrianRomanski]

@ timdeschryver

i pushed first changes :) Tommorrow i will do the remaining

[timdeschryver]

@AdrianRomanski are you willing to address the remaining feedback?

[AdrianRomanski]

@timdeschryver yes, i will sit to this straight after the office

[timdeschryver]

There are some syntax errors, and the sections also contain references to modules.
Because I can't references as comments, I will push a few commits to resolve this.

[markostanimirovic]

Thanks @AdrianRomanski!