minor #6106 Remove repetition in text (dominikhajduk)

This PR was merged into the 2.8 branch.

Discussion
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Remove repetition in text

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.8
| Fixed tickets |

Commits
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fcbcf1c Remove repetition in text

Author: xabbuh

Diff for: book/forms.rst

@@ -1170,7 +1170,7 @@ Defining your Forms as Services
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Your form type might have some external dependencies. You can define your form
-type as a service, and inject inject all dependencies you need.
+type as a service, and inject all dependencies you need.
 
 .. note::