Document that rvv-off feature is experimental and needs cmake

+ Use the exact same comment for it in both manifest files.

Author: EliahKagan

Cargo-zng.toml

@@ -39,9 +39,12 @@ libc = "0.2.43"
 cmake = "0.1.50"
 
 [features]
-# This feature builds riscv64 binaries portable to machines without RVV, even if the build machine
-# is riscv64 and detected to support RVV. This is useful for building a more portable binary, or on
-# systems where auto-detection is incorrect (as in https://github.com/zlib-ng/zlib-ng/issues/1705).
+# Experimental: This feature only affects zlib-ng, is only relevant to riscv64
+# targets, and currently only has an effect when `cmake` is used. It builds
+# binaries portable to machines without RVV, even if the build machine is
+# riscv64 and detected to support RVV. This is useful for building a more
+# portable binary, or on systems where auto-detection is incorrect
+# (as in https://github.com/zlib-ng/zlib-ng/issues/1705).
 rvv-off = []
 
 [lints.rust]

Cargo.toml

@@ -89,9 +89,10 @@ zlib-ng = ["libc", "cmake"]
 # or be completely removed in the future
 zlib-ng-no-cmake-experimental-community-maintained = ["libc"]
 stock-zlib = []
-# This feature only affects zlib-ng and is only relevant to riscv64 targets. It
-# builds binaries portable to machines without RVV, even if the build machine
-# is riscv64 and detected to support RVV. This is useful for building a more
+# Experimental: This feature only affects zlib-ng, is only relevant to riscv64
+# targets, and currently only has an effect when `cmake` is used. It builds
+# binaries portable to machines without RVV, even if the build machine is
+# riscv64 and detected to support RVV. This is useful for building a more
 # portable binary, or on systems where auto-detection is incorrect
 # (as in https://github.com/zlib-ng/zlib-ng/issues/1705).
 rvv-off = []