Correct misspellings in bulk sample registration docs

[tjmadonna]

rui_location description in bulk sample registration documentation reads:

This field is requred for all block level registrations. This is the JSON output from the [location Registrion User Interface Tool (RUI)](https://hubmapconsortium.github.io/ccf-ui/rui/), spatially locating the block inside the organ of origin. See the [RUI Demo](https://www.youtube.com/watch?v=142hGer4xvU) for instruction on how to register a location and obtain the JSON representation.

Required and Registration are misspelled

https://github.com/hubmapconsortium/documentation/blob/main/docs/bulk-registration/sample-bulk-reg.md