ENG-815: Add docs for multiple filters same field

[calummoore]

No description provided.

[linear]

ENG-815 Enable multiple where queries for the same field

Currently index field gets overwritten, the following can be added once this is fixed.

### Starts with

Using the `>=` and `<` operators, you can filter records that start with a given prefix.

```js
import { Polybase } from "polybase/client"

const db = new Polybase({ defaultNamespace: "your-namespace" });
const collectionReference = db.collection("cities");


// Starts with UK
const startsWithUK = await collectionReference
  .where("country", ">=", "UK")
  .where("country", "<", "UK~")
  .get();

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