MAINT: Add dev/release explanation to test script

Author: bluss

scripts/all-tests.sh

@@ -8,6 +8,7 @@ CHANNEL=$2
 
 ([ "$CHANNEL" != "beta" ] || (rustup component add rustfmt && cargo fmt --all -- --check))
 cargo build --verbose --no-default-features
+# Testing both dev and release profiles helps find bugs, especially in low level code
 cargo test --verbose --no-default-features
 cargo test --release --verbose --no-default-features
 cargo build --verbose --features "$FEATURES"