Fix typo for experiment ids array on projectConfig events

[alycecristines]

Summary

• When I was using the optimizely client I saw a problem related to type for the getOptimizelyConfig.events object. Since the type inform that the object is

export type OptimizelyEvent = {
    id: string;
    key: string;
    experimentsIds: string[];
};

but the reality it returns

export type OptimizelyEvent = {
    id: string;
    key: string;
    experimentIds: string[]; // singular
};

Test plan

Issues

• Fixes [BUG] Typo in Type Definition: experimentsIds should be experimentIds #991