Update readme for Edit+create action

[Gojo-Taqi]

Need:

Its not evident that id column need to be mentioned for Edit+create of CSV location upload. Not mentioning the id field will create the location and hence causing confusion.

Acceptance criteria:

Update readme here such that whoever does Edit+create of locations understand that id(uuid) field is needed.

Analysis

Sample file data for create and update
create.csv
State,District,Taluka,GP/Village,Dam
Uttar Pradesh,Bareilly,BT1,BGP1,BD1

edit.csv
State,District,Taluka,GP/Village,Dam,id
Uttar Pradesh,Bareilly,BT1,BGP1,BD1,df9abe2c-b635-4ad4-8209-103d2d4c982e

[arjunk]

There is no uuid mentioned in this file? How does the system understand which entity is to be updated? Does it find by the hierarchy combination? I couldn't find the documentation for the update scenario here https://avni.readme.io/docs/upload-data. Am i not seeing it at the right place or is it missing? If missing a good first step would be to update the documentation to describe the expected behaviour of the product.