Replace curly brackets with HTML representation

[Lawrence]

Under api.md, Docusaurus doesn't render the curly brackets for:

<dt>customProps?: Object = {}</dt>

The HTML equivalent must be used, such as:

<dt>customProps?: Object = &#123;&#125;</dt>

[Anthony Frehner]

thanks for the report. Do you mind making a PR to fix this? hopefully it's easy -- at the bottom of each page there is a Edit this page link that should take you directly to the .md file on github.