Add documentation around the links metadata handling from the aws-lc(-fips)-sys crate.

        println!("cargo:rustc-cfg=awslc");

        println!("cargo:awslc=true");

        // The aws-lc-sys and aws-lc-fips-sys crate use a link name that embeds

        // the version number of crate. Examples (crate-name => links name):

        //   * aws-lc-sys => aws_lc_0_26_0

        //   * aws-lc-fips-sys => aws_lc_fips_0_13_3

        // This is done to avoid issues if the cargo dependency graph for an application

        // were to resolve to multiple versions for the same crate.

        //

        // Due to this we need to determine what version of the AWS-LC has been selected (fips or non-fips)

        // and then need to parse out the pieces we are interested in ignoring the version componenet of the name.

        let env_var_prefix = match (is_aws_lc, is_aws_lc_fips) {

            (true, false) => "DEP_AWS_LC_",

            (false, true) => "DEP_AWS_LC_FIPS_",

        }

        let version = version.expect("aws-lc version detected");

        // Read the OpenSSL configuration statements and emit rust-cfg for each.

        if let Ok(vars) = std::env::var(format!("{env_var_prefix}{version}_CONF")) {

            for var in vars.split(',') {

                println!("cargo:rustc-cfg=osslconf=\"{var}\"");

            println!("cargo:conf={vars}");

        }

        // Emit the include header directory from the aws-lc(-fips)-sys crate so that it can be used if needed

        // by crates consuming openssl-sys.

        if let Ok(val) = std::env::var(format!("{env_var_prefix}{version}_INCLUDE")) {

            println!("cargo:include={val}");

        }