Incomplete documentation for features such as folder upload in Box Uploader element

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**Environment:**

- Elements version: 13.0.0

**Desktop (please complete the following information):**
N.A.
- OS: [e.g. Windows 10]
- Browser [e.g. chrome, safari]
- Version [e.g. 22]

**Smartphone (please complete the following information):**
N.A.
- Device: [e.g. iPhone6]
- OS: [e.g. iOS8.1]
- Browser [e.g. stock browser, safari]
- Version [e.g. 22]

**Steps to reproduce the problem:**
N.A.
**What is the expected behavior? (Screenshots can be helpful here)**
Documentation provides the full overview of the features and properties that can be configured.
**What went wrong? (Screenshots, console logs, or HAR files can be helpful here)**
The documentation is incomplete/outdated.
For example, we are trying to make use of Box Explorer as a Javascript library. We could not find any documentation on Folder upload feature but from the code and our testing, it is working.

**Link to application or sample code:**

**If relevant, link to file (or attach file here)**

**Expected behavior**
A clear and concise description of what you expected to happen.
We are expecting to have proper documentation on the[ developer guide](https://developer.box.com/guides/embed/ui-elements/uploader/) or [github readme](https://github.com/box/box-ui-elements/blob/master/src/elements/content-uploader/README.md).

For example, we would like to see important possible properties like "isFolderUploadEnabled" ( from https://github.com/box/box-ui-elements/blob/master/src/elements/content-uploader/ContentUploader.js)
at mentioned place.

**Screenshots**
N.A.

**Additional context**
Add any other context about the problem here.
N.A.