Update outdated readme for natives.

native/README.md

@@ -5,16 +5,28 @@ traditional Java fallbacks.
 
 ## Compression
 
-* **Supported platforms**: macOS 10.13, Linux amd64 (precompiled binary is built on Debian 9 with JDK 8)
+* **Supported platforms**: Linux x86_64 and aarch64, with Java 11 `ByteBuffer` API support as a fallback.
+  Compiled on CentOS 7.
 * **Rationale**: Using a native zlib wrapper, we can avoid multiple trips into Java just to copy memory around.
 
 ## Encryption
 
-* **Supported platforms**: macOS 10.13, Linux amd64
+* **Supported platforms**: Linux x86_64 (OpenSSL 1.0.x and OpenSSL 1.1.x) and aarch64 (OpenSSL 1.1.x only)
 * **Rationale**: Using a C library for encryption means we can limit memory copies. Prior to Java 7, this was the only
   way to use AES-NI extensions on modern processors, but this is less important since JDK 8 has native support.
-* **Note**: Due to U.S. restrictions on cryptography export, this native is provided in source code form only for now.
+* OpenSSL is not included in Velocity. Every distribution provides it now. To deal with ABI incompatibilities,
+  the native library (which only calls into OpenSSL and contains no cryptographic code) are available for
+  CentOS 7 (OpenSSL 1.0.0-based) and Debian 9 (OpenSSL 1.1.0-based) to provide the widest, most reasonable
+  compatibility with most modern distributions.
 
 ## OS support
 
-If you are on Alpine Linux, `apk add libc6-compat` will enable native support.
+The natives intend to have the widest possible range of compatibility with modern Linux distributions
+(defined as those being released in or after 2014).
+
+In theory, these libraries can be compiled for any Unix-like system (in the past, we supported macOS),
+but interest in other systems is minimal at best, thus we focus on Linux x86_64 and aarch64 as they
+are commonly used platforms.
+
+There is no support for Alpine Linux, however using `apk add libc6-compat` may enable native support.
+Alpine Linux support is on a "best-effort" basis only.