Auto merge of #6345 - dlaehnemann:docs_correct-profile-usage-info, r=ehuss

docs: correct profile usage of `cargo test --release`

From trying it out on a project (see <varlociraptor/varlociraptor#54 (comment)>), I have realised that the `profile` usage by `cargo test --release` differs from what is documented in the cargo book. So here comes my correction suggestion...

Author: bors

src/doc/src/reference/manifest.md

@@ -341,7 +341,8 @@ incremental = true # whether or not incremental compilation is enabled
 overflow-checks = true # use overflow checks for integer arithmetic.
                    # Passes the `-C overflow-checks=...` flag to the compiler.
 
-# The release profile, used for `cargo build --release`.
+# The release profile, used for `cargo build --release` (and the dependencies
+# for `cargo test --release`,  including the local library or binary).
 [profile.release]
 opt-level = 3
 debug = false
@@ -353,7 +354,8 @@ panic = 'unwind'
 incremental = false
 overflow-checks = false
 
-# The testing profile, used for `cargo test`.
+# The testing profile, used for `cargo test` (for `cargo test --release` see
+# the `release` and `bench` profiles).
 [profile.test]
 opt-level = 0
 debug = 2
@@ -365,7 +367,8 @@ panic = 'unwind'
 incremental = true
 overflow-checks = true
 
-# The benchmarking profile, used for `cargo bench` and `cargo test --release`.
+# The benchmarking profile, used for `cargo bench` (and the test targets and
+# unit tests for `cargo test --release`).
 [profile.bench]
 opt-level = 3
 debug = false