v1.2: Code sample changes

[maryamsulemani97]

1. Add get_documents_post_1 https://github.com/meilisearch/documentation/pull/2421

   curl \
   -X POST http://localhost:7700/indexes/books/documents/fetch \
   -H 'Content-Type: application/json' \
   --data-binary '{ 
     "filter": "(rating > 3 AND (genres = Adventure OR genres = Fiction)) AND language = English",
     "fields": ["title", "genres", "rating", "language"],
     "limit": 3
   }'

2. Add delete_documents_by_filter_1 https://github.com/meilisearch/documentation/pull/2421

   curl \
   -X POST http://localhost:7700/indexes/movies/documents/delete \
   -H 'Content-Type: application/json' \
   --data-binary '{
     "filter": "genres = action OR genres = adventure"
   }'

3. Update get_documents_1 https://github.com/meilisearch/documentation/pull/2421

   curl \
   -X GET 'http://localhost:7700/indexes/movies/documents?limit=2&filter=genres=action'

4. Rename delete_documents_1 to delete_documents_by_batch_1

[maryamsulemani97]

@brunoocasali

This issue contains all v1.2 code sample changes. Could you please move it to the integration guide repo?

[brunoocasali]

The release was completed! Thanks team! 🎉 🎉