* Documentation: Remove XHTML spec and fix errors
None of the docs follow the XHTML specification, which means
that programs that expect this (such as Gnome Web) as it is advertised
as such, will completely fail to parse it as it is incorrect syntax. So
it is removed.
* Remove .chm files
The cascade order has been updated so that SM4 is applied after the other cipher(s) (e.g., Serpent). This change reflects standard cryptanalytic guidance, which shows that the overall strength of a cascade is limited by the first encryption stage. Given that SM4 uses a 128-bit key, its post-quantum brute-force resistance is lower than ciphers with a 256-bit key (such as Serpent). By placing SM4 last, we ensure that any potential weakness in SM4 cannot reduce the security margin provided by the stronger cipher.
