Fix documentation example for using `searchUsersByCredentials` action.

[azagaya]

What does this PR do ?

Fixes a small mistake in the documentation.

How should this be manually tested?

Step 1: Try to do a searchUsersBycredentials query as the documentation states, see it fails. Step 2: Try with my proposed changes, and it works.

[sonarqubecloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[kuzzle]

:tada: This PR is included in version 2.30.1-beta.1 :tada:

The release is available on:

• npm package (@beta dist-tag)
• GitHub release

Your semantic-release bot :package::rocket:

[kuzzle]

:tada: This PR is included in version 2.31.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: