Mismatch between CORS_HEADER_403_CONTENT_TYPE in ALPINE Dockerfile and README documentation

[perotto]

Hi,

I noticed a discrepancy between the ALPINE Dockerfile and the project documentation regarding the CORS_HEADER_403_CONTENT_TYPE environment variable.

In nginx/Dockerfile-alpine, the value appears to be set differently at line 139: https://github.com/coreruleset/modsecurity-crs-docker/blob/main/nginx/Dockerfile-alpine#L139

In the main Dockerfile, the corresponding value at line 137 is different: https://github.com/coreruleset/modsecurity-crs-docker/blob/main/nginx/Dockerfile#L137

However, the README documents CORS_HEADER_403_CONTENT_TYPE as text/html: https://github.com/coreruleset/modsecurity-crs-docker/blob/main/README.md?plain=1#L249

This creates ambiguity about the expected default value, especially for users relying on the ALPINE image.

Expected behavior:

The ALPINE Dockerfile should match the documented default value, or the README should be updated to reflect the actual intended value.

Actual behavior:

The ALPINE Dockerfile uses a different value from the one documented in the README.

Impact:

This may lead to inconsistent behavior between image variants and confusion for users configuring CORS-related headers.

Would it be possible to align the ALPINE Dockerfile with the documentation, or clarify which value should be considered canonical?

Thanks!