Update sql guide

[cpcgoogle]

Add a reference to the SQL for application best practices documentation.

[gemini-code-assist]

Code Review

This pull request updates the Bigtable SQL guide to recommend using SQL functions for data manipulation before implementing custom client-side logic, and adds a link to the application development guide. The reviewer suggested fixing a double-space typo and using more descriptive link text to improve accessibility and readability.

[gemini-code-assist]

There is a double space in on using. Additionally, using "this [guide]" as link text is less descriptive. It is better to use more descriptive link text for improved readability and accessibility.

Suggested change

Bigtable offers a wide range of [SQL functions](https://docs.cloud.google.com/bigtable/docs/reference/sql/functions-all) and [operators](https://docs.cloud.google.com/bigtable/docs/reference/sql/operators) and [conditional expressions](https://docs.cloud.google.com/bigtable/docs/reference/sql/conditional_expressions). When developing an application using Bigtable, you should always consider if the data manipulation can be performed using a SQL function before trying to develop the logic in the client application. For best practices on using Bigtable SQL from an application, see this [guide](https://docs.cloud.google.com/bigtable/docs/googlesql-develop-apps) that explains how to create the client, prepare the query, and read the results.

Bigtable offers a wide range of [SQL functions](https://docs.cloud.google.com/bigtable/docs/reference/sql/functions-all) and [operators](https://docs.cloud.google.com/bigtable/docs/reference/sql/operators) and [conditional expressions](https://docs.cloud.google.com/bigtable/docs/reference/sql/conditional_expressions). When developing an application using Bigtable, you should always consider if the data manipulation can be performed using a SQL function before trying to develop the logic in the client application. For best practices on using Bigtable SQL from an application, see the [guide on developing applications with GoogleSQL](https://docs.cloud.google.com/bigtable/docs/googlesql-develop-apps) that explains how to create the client, prepare the query, and read the results.