docs(README): remove extra space in variable syntax in README example (#201)
### Fix syntax error in GitHub Actions example in README
This PR fixes a syntax error in the "Create a git committer string for
an app installation" example in the README file.
#### What was wrong?
The example contained an incorrect space in the variable syntax:
```yaml
${ {steps.committer.outputs.string }}
```
This caused the example to fail, as GitHub Actions does not allow spaces
in variable interpolation.
#### What was fixed?
The syntax was corrected to:
```yaml
${{ steps.committer.outputs.string }}
```
This fix ensures that users can copy and use the example without
encountering any errors.
This commit is contained in:
Carlos García