fix: rename create_collection indexes->index + doc notes (mongo-3/4/5)

- mongo-3: create_collection param renamed indexes -> index (it seeds ONE index; a key-spec
  builds one compound index, not two). update keyword call sites indexes= -> index=.
- mongo-4: docstring notes an instance is single-use after close() (pymongo 4.x close is
  irreversible; connect() only pings).
- mongo-5: docstring notes construction may raise InvalidURI for a malformed URI.
- README: create_collection index note. bump v0.1.5 -> v0.1.6

Signed-off-by: disqualifier <dev@disqualifier.me>

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "mongo"
-version = "0.1.5"
+version = "0.1.6"
 description = "async mongodb wrapper over motor with a raw escape hatch"
 requires-python = ">=3.10"
 dependencies = [