Implement Rustdoc versioning checks
Implement Rustdoc versioning checks

Before compiling, we need to make sure that if there
were any previous docs already compiled, they were
compiled with the same Rustc version that we're
currently using. Otherways we must remove the
`doc/` folder and compile again.

This is important because as stated in #8461
the .js/.html&.css files that are generated
by Rustc don't have any versioning.
Therefore, we can fall in weird bugs and behaviours
if we mix different compiler versions of these
js/.html&.css files.

rustyhorde/cargo,rustyhorde/cargo,eminence/cargo,rust-lang/cargo,nipunn1313/cargo,rust-lang/cargo,nipunn1313/cargo,rust-lang/cargo,eminence/cargo,nipunn1313/cargo,rust-lang/cargo,rustyhorde/cargo,eminence/cargo,nipunn1313/cargo,eminence/cargo,rustyhorde/cargo