package overview page is unaccessible from text/HTML help

[bastistician]

https://github.com/thomasp85/densityClust/blob/2261766cdf9ed6c5bf51556398e95cffb903c796/man/densityClust-package.Rd#L3-L5

The package overview help page lacks the conventional \alias{<pkgname>-package} topic, which means:

• it is missing from the HTML index
• it is not found via package?<pkgname> and cannot be easily accessed from text/HTML help

(It is included in the PDF manual, though.)