[website][ru]: Fix warning

[fernape]

Summary

"level 0 sections can only be used when doctype is book"

This comes from this review https://reviews.freebsd.org/D53041 that for some reason I'm not allowed to see.

In theory I think these comments should be ignored according to https://docs.asciidoctor.org/asciidoc/latest/document/header/#header-requirements-per-doctype but the fact is that they aren't .

[vladlen]

We already discussed this issue internally, it must be fixed.
The technical reason of this error - though the document is in AsciiDoc format, the block delimited by --- is considered as YAML language block (assignment of 2 variables: title and sidenav), and --- must start at the 1st line of the file, otherwise it will be considered as AsciiDoc code with wrong syntax. That comment about original hash should be placed somewhere inside of the document.

[andy]

Colleagues,

Take a look at the https://reviews.freebsd.org/D53187

It contains the fixes and update to the latest original version.