[DOCS]: "every drizzle driver now has drizzle.mock()" is not true

### Enhancement hasn't been filed before.

- [x] I have verified this enhancement I'm about to request hasn't been suggested before.

### Describe the enhancement you want to request

https://orm.drizzle.team/docs/goodies#mock-driver

```ts
import type { D1Database } from "@cloudflare/workers-types";
import { drizzle } from "drizzle-orm/d1";
import * as schema from "./schema";

export const createDb = (d1: D1Database) => drizzle(d1, { schema });

// Separate function for testing purposes
export const createMockDb = () => drizzle.mock({ schema });
// error: Property 'mock' does not exist on type ' = Record, TRelations extends AnyRelations = EmptyRelations, TClient extends AnyD1Database = D1Database>(client: TClient, config?: DrizzleConfig) => DrizzleD1Database<...> & { ...; }'.
```

Not true for a whole host of drivers (as of latest `main` `6ab1bbea`):

```sh
for file in $(find drizzle-orm/src -name "driver.ts"); do
if grep -q "export function mock" "$file"; then
echo "✓ FOUND: $file"
else
echo "✗ MISSING: $file"
fi
done
```
```
✓ FOUND: drizzle-orm/src/aws-data-api/pg/driver.ts
✓ FOUND: drizzle-orm/src/better-sqlite3/driver.ts
✓ FOUND: drizzle-orm/src/bun-sql/driver.ts
✓ FOUND: drizzle-orm/src/bun-sqlite/driver.ts
✓ FOUND: drizzle-orm/src/gel/driver.ts
✓ FOUND: drizzle-orm/src/libsql/driver.ts
✓ FOUND: drizzle-orm/src/mysql2/driver.ts
✓ FOUND: drizzle-orm/src/neon-http/driver.ts
✓ FOUND: drizzle-orm/src/neon-serverless/driver.ts
✓ FOUND: drizzle-orm/src/node-postgres/driver.ts
✓ FOUND: drizzle-orm/src/pglite/driver.ts
✓ FOUND: drizzle-orm/src/planetscale-serverless/driver.ts
✓ FOUND: drizzle-orm/src/postgres-js/driver.ts
✓ FOUND: drizzle-orm/src/singlestore/driver.ts
✓ FOUND: drizzle-orm/src/tidb-serverless/driver.ts
✓ FOUND: drizzle-orm/src/vercel-postgres/driver.ts
✗ MISSING: drizzle-orm/src/d1/driver.ts
✗ MISSING: drizzle-orm/src/durable-sqlite/driver.ts
✗ MISSING: drizzle-orm/src/expo-sqlite/driver.ts
✗ MISSING: drizzle-orm/src/mysql-proxy/driver.ts
✗ MISSING: drizzle-orm/src/op-sqlite/driver.ts
✗ MISSING: drizzle-orm/src/pg-proxy/driver.ts
✗ MISSING: drizzle-orm/src/prisma/mysql/driver.ts
✗ MISSING: drizzle-orm/src/prisma/pg/driver.ts
✗ MISSING: drizzle-orm/src/prisma/sqlite/driver.ts
✗ MISSING: drizzle-orm/src/singlestore-proxy/driver.ts
✗ MISSING: drizzle-orm/src/sql-js/driver.ts
✗ MISSING: drizzle-orm/src/sqlite-proxy/driver.ts
✗ MISSING: drizzle-orm/src/xata-http/driver.ts
```

16 drivers support `.mock`, 13 don't