CMS: Adds documentation for HMACSecretKey to Imaging Settings

[iOvergaard]

Description

Added section about HMACSecretKey to secure image requests. This has been a feature since V12, so it updates all articles since then.

Type of suggestion

• Typo/grammar fix
• Updated outdated content
• New content
• Updates related to a new version
• Other

Product & version (if relevant)

13, 14, 15, 16

Deadline (if relevant)

ASAP

[Copilot]

Pull Request Overview

This PR adds documentation for the HMACSecretKey configuration used to secure image requests. The changes update reference articles for versions 13 through 16 by introducing the new HMACSecretKey setting and providing example configuration code and usage instructions.

• Added HMACSecretKey setting to the JSON configuration and its documentation.
• Included an example using the IOptions pattern with a code snippet to generate a secure random key.
• Updated documentation across multiple version folders (13, 14, 15, 16) to reflect these changes.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
16/umbraco-cms/reference/configuration/imagingsettings.md	Added HMACSecretKey setting and documentation section, including sample code.
15/umbraco-cms/reference/configuration/imagingsettings.md	Added HMACSecretKey setting and documentation section, including sample code.
14/umbraco-cms/reference/configuration/imagingsettings.md	Added HMACSecretKey setting and documentation section, including sample code.
13/umbraco-cms/reference/configuration/imagingsettings.md	Added HMACSecretKey setting and documentation section, including sample code.

Comments suppressed due to low confidence (4)

16/umbraco-cms/reference/configuration/imagingsettings.md:87

• [nitpick] Consider updating the header to use consistent capitalization ('HMACSecretKey') to match the configuration property.

## Hmac secret key

15/umbraco-cms/reference/configuration/imagingsettings.md:87

• [nitpick] Consider standardizing the header text to 'HMACSecretKey' to maintain consistency with the property name.

## Hmac secret key

14/umbraco-cms/reference/configuration/imagingsettings.md:87

• [nitpick] Update the header to 'HMACSecretKey' for consistency with the configuration property name.

## Hmac secret key

13/umbraco-cms/reference/configuration/imagingsettings.md:87

• [nitpick] Update the header text to 'HMACSecretKey' to match the naming convention used in the configuration properties.

## Hmac secret key

[eshanrnh]

Thanks for the PR, @iOvergaard 🙌 The PR looks great.

I've made some minor suggestions as per the styleguide for v13 which I'll incorporate. Can you make these changes for the rest of the versions, please?

[iOvergaard]

Thanks for the PR, @iOvergaard 🙌 The PR looks great.

I've made some minor suggestions as per the styleguide for v13 which I'll incorporate. Can you make these changes for the rest of the versions, please?

Done :-)

[eshanrnh]

Awesome, Thanks 🙌