Billing docs: add managing payment methods page

[Blargian]

Summary

Closes DOC-699

Checklist

• Delete items not relevant to your PR
• URL changes should add a redirect to the old URL via https://github.com/ClickHouse/clickhouse-docs/blob/main/docusaurus.config.js
• If adding a new integration page, also add an entry to the integrations list here: https://github.com/ClickHouse/clickhouse-docs/blob/main/docs/integrations/index.mdx

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Project	Deployment	Actions	Updated (UTC)
clickhouse-docs	Ready	Preview	Apr 8, 2026 4:52pm

[rsickles]

Small changes:

• Update this sentence to this - "All services in the organization you want to bill via Marketplace subscription must be on the same cloud provider as the marketplace (AWS, GCP or Azure)."
• Anywhere that says "Navigate to Settings > Billing in the ClickHouse Cloud console." change to "Navigate to the Billing page in the ClickHouse Cloud console."

Thanks for tackling this one so quickly @Blargian !

[rsickles]

@Blargian also two more changes below -

• For the second screenshot under section "Steps to add or update your credit card" can we use this instead?

- Then add a note block under section "Steps to add a backup credit card" with the text that says "After configuring a backup credit card you will also have the option to click on the button to edit your credit card and set it as the primary payment method. However, if you do this, your credit card will become your only payment method for the organization and your Marketplace subscription will be completely removed from ClickHouse Cloud. You will need to go back into your marketplace account to reconfigure it based on the steps in the section "Set up marketplace billing from your cloud provider"."