STRUCTURE/NEW - Improve docs on combining Lookit consent with external study

[becky-gilbert]

Currently the documentation gives some explanations of internal vs external study types here:
https://lookit.readthedocs.io/en/develop/index.html?highlight=internal#what-is-lookit
and here:
https://lookit.readthedocs.io/en/develop/researchers-set-study-fields.html?highlight=query#external

However, researchers might find it helpful if we explain some more nuanced options for combining internal and (async) external study types (thanks Lillian Xu for suggesting this on slack!). For example, we could point out that researchers can:

• embed an externally-hosted study (e.g. Qualtrics) within a Lookit internal study
• start the session as an internal study (e.g. to get a consent video) and later redirect to an externally-hosted portion

Given these different options, it might also help researchers if we give our thoughts/guidance on making decisions about internal vs external studies, including the important considerations from our point of view such as family experience and data privacy.

WRT implementation of combined internal/external studies, we could provide one or more example studies showing exactly how to do this (thanks @msheskin for the suggestion!).

A related issue is that, while looking into this, I found it a little hard to pull out the parts of the documentation that are relevant to internal vs external studies. Right now I think the beginning of the documentation is mostly related to both study types, but then they diverge at "Protocol specification" (2nd page under "Creating Your Study" section). We might be able to make the documentation easier for researchers to navigate by flagging various sections/pages as only being related to internal vs external study types.

Ideas for addressing the issues above:

• Add a new page under the "Overview" or "Using Lookit" section that goes into more detail about internal vs external study types, as well as options for combining them and passing session/ID info between platforms. We could include some example code here if it makes sense.
• Add a new "Tutorial" section for (1) embedding external platforms in internal studies, and/or (2) redirecting from an internal study to an external platform.
• Add a new combined internal/external example study to the platform that researchers can access and reference.
• Clarify which parts of the documentation are specific to either internal or external study types. Maybe we could use Internal/External subheadings under "Creating Your Study", or split this section into two or more sections: "Creating Your Study - Internal", "Creating Your Study - External", "Creating Your Study - Combining Internal and External".

If anyone has thoughts on this, please feel free to add them to this issue thread!