Added an FAQ about choosing between custom and base DC (#552)

* add FAQ

* add link to main FAQ

* simplify wording

* change wording

* update data request instruction

* fix HTML to Markdown

custom_dc/faq.md

@@ -13,6 +13,16 @@ parent: Build your own Data Commons
 
 ## General questions
 
+### Should I contribute my data to the base Data Commons or should I run my own instance?
+
+If you have determined that your data is a [good fit for Data Commons](https://datacommons.org/faq.html#fit), the main considerations for whether to host your data in the base Data Commons or in your own custom instance are as follows:
+- If you have any private data, or you want to restrict access to your data, you must use your own instance.
+- If you want to maintain governance and licensing over your data, you should use your own instance.
+- If you want to control the UI of the website hosting your data, use your own instance.
+- If you want the widest possible visibility of your data, including direct access through Google Search, add your data to base Data Commons.
+
+For detailed comparison on the differences between base and custom Data Commons, see the [Overview](/custom_dc/index.html#comparison) page.
+
 ### How can I request new features or provide feedback?
 
 Please see [Send feedback](/custom_dc/index.html#feedback) for details.

custom_dc/index.md

@@ -30,9 +30,10 @@ If you have the resources to develop and maintain a custom Data Commons instance
 
 For the following use cases, a custom Data Commons instance is not necessary:
 
-- You only want to make your own data available to the base public Data Commons site and don't need to test it. In this case, see the procedures in [Data imports](/import_dataset/index.html).
+- You want to share your data publicly on datacommons.org. In this case, please file a [data request](https://issuetracker.google.com/issues/new?component=1660823&template=2053232){: target="_blank"} in our issue tracker to get started.
 - You want to make the base public data or visualizations available in your own site. For this purpose, you can call the Data Commons APIs from your site; see [Data Commons web components](/api/web_components/index.html) for more details.
 
+{: #comparison }
 ## Comparison between base and custom Data Commons
 
 | Feature                                                      |  Base Data Commons | Custom Data Commons |