docs: fix typo in dependency injection guide

[ashinzekene]

Fixed typo

HeroService must provided in some parent injector
HeroService must be provided in some parent injector

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have 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
• Documentation content changes
• angular.io application / infrastructure changes
• Other... Please describe:

What is the current behavior?

HeroService must provided in some parent injector

Issue Number: N/A

What is the new behavior?

HeroService must be provided in some parent injector

Does this PR introduce a breaking change?

• Yes
• No

Other information

HeroService must provided in some parent injector
HeroService must be provided in some parent injector

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[brandonroberts]

Update git commit message to docs: fix typo in dependency injection guide

[brandonroberts]

Thanks for the PR @ashinzekene! You must sign the CLA before this PR can move forward. You also need to update the git commit message.

After this PR gets reviewed, is approved, and is green on CI, its ready to merge.

[googlebot]

CLAs look good, thanks!

[ashinzekene]

Done @brandonroberts

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