Create API call examples to create and edit Wikidata works and authors items

Fixe

Fixes microtask T405635

Description

Creates a basic markdown file named api-calls-example.md with examples of API calls to create and edit work and author items. The file contains 4 examples:

1. An example API call to create an author item
2. An example API call to create a work item
3. An example API call to add a statement to the already created author item
4. An example API call to modify the already created item's statement to another

Checklist

• Read the documentation related to the Wikibase REST API
• Set up authorisation using an OAuth 2.0 client, following these steps: https://www.wikidata.org/wiki/Wikidata:REST_API/Authentication
• Experiment with the item creation page to identify the correct properties and content values for creating test items
• Create an author test item (changed the "country of residence" (P196) of "Uruguay" (Q208648) to "Bolivia" (Q208640).
• Create a work test item

Screenshots

What the api-call-examples.md file contains: