Added docs for Monzo integration (home-assistant#29279)

* Added docs for Monzo integration

* Clarified oauth client setup

* Add guide for adding a second account

* Tiny style tweaks

* Style tweaks: use numbered steps for procedural content

* fix indent

* fix indent

* Add link to remote access documentation

* Fix indents

* Remove ToC.

* Move config flow after prerequisites

* Update release

* Fix typo

* Put URL clarification in correct step

* Temporarily remove missing features

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Co-authored-by: c0ffeeca7 <[email protected]>

source/_integrations/monzo.markdown

@@ -0,0 +1,56 @@
+---
+title: Monzo
+description: Instructions on how to integrate Monzo integration into Home Assistant.
+ha_category:
+  - Sensor
+ha_release: 2024.6
+ha_iot_class: Cloud Polling
+ha_codeowners:
+  - '@JakeMartin-ICL'
+ha_config_flow: true
+ha_domain: monzo
+ha_homekit: true
+ha_platforms:
+  - sensor
+---
+
+The **Monzo** {% term integration %} allows you to connect your Monzo bank accounts to Home Assistant.
+
+
+## Prerequisites and approval
+
+1. Before adding the Monzo integration, you'll need to create a [Monzo developer account](https://developers.monzo.com/). 
+2. From here, you need to create a new OAuth client for Home Assistant to use by going to **Clients** > **New OAuth Client**. 
+3. Then, fill in the form as follows, making sure to **copy the URL shown** - don't replace it with your own URL:
+   - Name: Home Assistant
+   - Logo URL: This can be left blank
+   - Redirect URLs: <https://my.home-assistant.io/redirect/oauth>
+   - Description: For example: Used by the Monzo Home Assistant Integration
+   - Confidentiality: Confidential
+
+4. Once submitted, you can proceed with adding the integration.
+   - Go to {% my integrations title="**Settings** > **Devices & services**" %}, and add the **Monzo** integration.
+   - Fill in the OAuth details for the client you've created in the Monzo developer portal.
+   - **Important** - After authorizing Home Assistant access via email, for security you'll also need to verify again from within the Monzo app. 
+     - A reminder to do this will be displayed in Home Assistant before completing the installation - don't proceed until you've done this from the popup in the mobile app.
+     - If you've forgotten to do this, the integration will fail to load, but you can simply accept the popup and reload the integration without entering your details again.
+
+{% include integrations/config_flow.md %}
+
+### Adding a second account
+
+1. To add a second Monzo account in Home Assistant, repeat the above process for creating an OAuth client.
+2. Then, in Home Assistant, add the new credentials *before* trying to add the new entry. 
+   - In the top right of **Devices & Services** page, select the three dot menu, open **Application Credentials**, and select **Add application credentials**
+   - It is recommended to include the person's name in the *Name* field so you can distinguish it later. 
+3. Once added, you can return to **Devices & Services** > **Monzo** > **Add Entry** to proceed with authentication.
+
+## Sensor
+
+The integration will create a device for each of your accounts and pots. For an account or a pot, you'll have:
+
+- Balance: The current balance of the account.
+
+Additionally, an account will also have:
+
+- Total Balance: The current balance of that account plus all of its pots.