docs: rust: Add rusttest info

Searching the Rust kernel documentation all existing Rust Make
targets (rustavailable, rustfmt, rustfmtcheck, rustdoc and
rust-analyzer) are explicitly documented with their Make commands.
While the Make target rusttest is mentioned two times in the
existing documentation, it's Make command is not explicitly
documented, yet. Add a test section to document this.

While at it, add some info about the more important KUnit testing
too.

Reviewed-by: David Gow <[email protected]>
Signed-off-by: Dirk Behme <[email protected]>
Reviewed-by: Martin Rodriguez Reboredo <[email protected]>
Reviewed-by: Benno Lossin <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[ Added "the", newline and quotes for `.config`. Expanded "repos". ]
Signed-off-by: Miguel Ojeda <[email protected]>

0 files changed, 0 insertions, 0 deletions