docs: move feature explanation

Author: JyJyJcr

Cargo.toml

@@ -29,9 +29,11 @@ nginx-sys = { path = "nginx-sys", default-features=false, version = "0.5.0"}
 
 [features]
 default = ["vendored","std"]
-# use allocation
+# Enables the components using memory allocation.
+# If no `std` flag, `alloc` crate is internally used instead. This flag is mainly for `no_std` build.
 alloc = []
-# use std
+# Enables the components using `std` crate.
+# Currently the only difference to `alloc` flag is `std::error::Error` implementation.
 std = ["alloc"]
 # Build our own copy of the NGINX by default.
 # This could be disabled with `--no-default-features` to minimize the dependency tree

nginx-sys/README.md

@@ -16,9 +16,6 @@ nginx-sys = "0.5.0"
 
 - `vendored`: Enables the build scripts to download and build a copy of nginx source and link against it.
   This feature is enabled by default.
-- `alloc`: Enables the components using memory allocation. If no `std` flag, `alloc` crate is internally used instead. This flag is mainly for `no_std` build.
-- `std`: Enables the components using `std` crate. Currently the available components are same to when specifying `alloc` only.
-  This feature is enabled by default.
 
 ## Output variables