Rollup merge of #69747 - spastorino:rename-rustc-guide, r=pietroalbini

Rename rustc guide

This is in preparation for https://github.com/rust-lang/rustc-guide/issues/470
Needs to be merged after we actually rename the guide.

Have used this to rename:

`git grep -l 'rustc_guide' | xargs sed -i 's/rustc_guide/rustc_dev_guide/g'`
`git grep -l 'rustc-guide' | xargs sed -i 's/rustc-guide/rustc-dev-guide/g'`
`git grep -l 'rustc guide' | xargs sed -i 's/rustc guide/rustc dev guide/g'`