Fix type-checking errors in snippets (code only, no .md)

This commit both:
- Fixes pre-existing mistakes in snippets, aka wrong code samples.
- Adds hidden (`@hide`) statements that do not appear in the docs,
  but satisfy typecheckers.

qdrant-landing/content/documentation/headless/snippets/fastembed/bm25/upsert-points/python.py

@@ -2,6 +2,8 @@ from qdrant_client import QdrantClient, models  # @hide
 
 client = QdrantClient(url="http://localhost:6333")  # @hide
 
+documents: list[str] = [] # @hide
+
 #Estimating the average length of the documents in the corpus
 avg_documents_length = sum(len(document.split()) for document in documents) / len(documents)