Blob's TOJSON Section is not the main use case and could lead to confusion

Reference: https://ibsoln.github.io/stage/stage300/couchbase-lite/current/csharp/document.html

Using Blob'S TOJSON() is not a common usecase and it's mainly for helping development of some binding language such as JavaScript. Providing a section and example there is just confusing users. If we want to provide into, it's better to have an entirely new section about binding development for CBL. I suggested to remove that section.