AddListener function fix in doc

[rubensflinco]

The example of the addListener function was wrong in doc.

Thanks for submitting a PR! Please read these instructions carefully:

• Explain the motivation for making this change.
• Provide a test plan demonstrating that the code is solid.
• Match the code formatting of the rest of the codebase.

Motivation (required)

What existing problem does the pull request solve?

Test Plan (required)

A good test plan has the exact commands you ran and their output, provides screenshots or videos if the pull request changes UI or updates the website. See What is a Test Plan? to learn more.

If you have added code that should be tested, add tests.

Next Steps

Sign the CLA, if you haven't already.

Small pull requests are much easier to review and more likely to get merged. Make sure the PR does only one thing, otherwise please split it.

Make sure all tests pass on Circle CI. PRs that break tests are unlikely to be merged.

For more info, see the "Pull Requests" section of our "Contributing" guidelines.

[facebook-github-bot]

Hi JotinhaBR! Thank you for your pull request and welcome to our community. We require contributors to sign our Contributor License Agreement, and we don't seem to have you on file.In order for us to review and merge your code, please sign at https://code.facebook.com/cla. If you are contributing on behalf of someone else (eg your employer), the individual CLA may not be sufficient and your employer may need to sign the corporate CLA.

If you have received this in error or have any questions, please contact us at cla@fb.com. Thanks!

[facebook-github-bot]

Thank you for signing our Contributor License Agreement. We can now accept your code for this (and any) Facebook open source project. Thanks!

[rubensflinco]

merge pull requests