I’ve forked Yii 2 apidoc and enabled it to generate API and guide documentation into appropriate CHM manual. It is based on existing apidoc Bootstrap theme, which is quite good-looking, and documentation search features were replaced with built-in CHM search.
You will need existing Microsoft Html Help Workshop installation to compile CHM from generated project files. There are ways to set up and run it via Wine in Linux/Mac environment.
There’s compiled CHM in releases, I will keep it updated for significant documentation changes.
I find Kchmviewer tolerable enough for what it should do. It doesn’t allowed js out of the box (should be enabled manually, it’s required for Bootstrap widgets), but otherwise it is fine.
Thank you for the help generating the Yii guide and API in chm. However, this newer version 2.0.10 does not contain material that is already online. For example, in the Widgets section, there is missing documentation for GridView, ListView, etc. while the online guide (http://www.yiiframework.com/doc-2.0/guide-README.html) includes them. It seems that the repository from which the chm help file is generated must be synced with the main doc repository (https://github.com/yiisoft/yii2/tree/master/docs/guide).