Incorrect usage on WebexActivity

[jonniespratley]

The docs are:

• Missing
• Needed
• Confusing
• Not Sure?

Give Us the Details

Explain what you didn't like about our current documentation.

For the example on https://github.com/webex/components/tree/master/src/components/WebexActivity#embed

It specifies to use

<WebexActivities .../>

it should be:

<WebexActivity .../>

Describe the solution you'd like

Let us know how we can help you make better use of our documentation.

Change docs to have:

<WebexActivity .../>

[lalli-flores]

We have a contribution model, mate! 😜 Feel free to open a PR