Tweak comments in Cargo sheet, add more frequently used commands

- New comment style avoids incorrect syntax highlighting

sheets/_rust/Cargo

@@ -1,30 +1,43 @@
-# Cargo is the Rust package manager
-# Cargo downloads your Rust project's dependencies,
-# compiles your project, makes packages, and upload them to crates.io
-# See also: https://doc.rust-lang.org/cargo/
+// Cargo is the Rust package manager. It downloads your Rust project's dependencies,
+// compiles your project, creates packages, and uploads them to crates.io.
+// See also: https://doc.rust-lang.org/cargo/
 
-# To start a new project
-cargo new hello_world --bin     # program
-cargo new hello_world --lib     # library
+// To create a blank application:
+cargo new hello_world // or cargo new --bin hello_world
 
-# Build a project without optimizations (in debug mode)
+// To create a blank library:
+cargo new --lib hello_world
+
+// Build a project without optimizations (in debug mode).
 cargo build
 
-# Build a project with optimizations turned on
+// Compile and check a project for errors (faster than cargo build)
+cargo check
+
+// Build a project with all optimizations turned on
 cargo build --release
 
-# Build and run (without optimizations) a package with Cargo
+// Build and run a binary application with Cargo (in debug mode).
 cargo run
 
-# Updates dependencies in Cargo.lock
-cargo update            # update all
-cargo update -p rand    # updates just “rand” crate
-
-# run the project tests (from src/ and tests/)
+// Run the project tests (from src/ and tests/)
 cargo test
 
-# Clean all output build files and targets
+// Generate rustdoc documentation for your package
+cargo doc
+
+// Publishes your package to the registry, using information from Cargo.toml
+cargo publish
+
+// Updates dependencies in Cargo.lock
+cargo update            // update all
+cargo update -p rand    // update just "rand" crate
+
+// Clean all build files
 cargo clean
 
-# search for a package
+// Search for a package
 cargo search
+
+// Build and install a binary package into ~/.cargo/bin/
+cargo install