Add markdown with Wikibase REST API call examples

Shreya-bhagatrequested to merge
shr0x-ya/paulina:T405635/api-call-examples into main

Closes T405635 Test Wikidata pages:

  1. https://test.wikidata.org/wiki/Q241620 (Testing creation of Author - similar to creation of a work item) Screenshot_from_2025-10-11_18-11-50
  2. https://test.wikidata.org/wiki/Q241621 (Testing addition of new Statement) task_2
  3. https://test.wikidata.org/wiki/Q241614 (Test changing a Statement Element: Country of origin changed from Uruguay to India) task_3

(2 & 3 were tested from windows system as I exhausted the daily limit of API requests on my Ubuntu system)

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