Property `htmlTemplate` is not expected here.

[mykel scappin]

Describe the bug
When executing redocly build-docs -o output.php on terminal, i get this unexpected output

[1] redocly.yaml:26:5 at #/theme/openapi/htmlTemplate

Property `htmlTemplate` is not expected here.

24 | theme:
25 |   openapi:
26 |     htmlTemplate: redoc_template/index.php
27 |

Warning was generated by the configuration spec rule.


⚠️ Your config has 1 warning.
Found redocly.yaml and using theme.openapi options

Expected behavior
This error should not be happening - that configuration in redocly.yaml seems to be correct and supported as per all the documentation.

Minimal reproducible OpenAPI snippet(if possible)
n/a

Screenshots
n/a

Additional context
n/a