Clarify the crypto notice for mod_session_crypto.

    general-purpose encryption library, such as OpenSSL, NSS, or the

    operating system's platform-specific facilities. This interface is

    known as the apr_crypto interface, with implementation beneath the

    /crypto directory.

    /crypto directory. The apr_crypto interface is used by the

    mod_session_crypto module available under

      modules/session

    for optional encryption of session information.

    Some object code distributions of Apache httpd, indicated with the

    word "crypto" in the package name, may include object code for the