Fix doc to clarify Lua availability (#794)

* Update compatibility.md

* Update compatibility.md

website/docs/welcome/compatibility.md

@@ -19,8 +19,9 @@ guideline on what differences you can expect when using Garnet.
 it as a transaction (stored procedure).
 2. Garnet does not support the Redis functions or modules. Instead, it has its own C# based extensibility mechanisms
 that are optimized for high performance and ease of use.
-3. Garnet does not support Lua scripting. We have an experimental version, but it was noted to be too slow for
-realistic use so we have not added it to the project.
+3. Garnet now has support for Lua scripting. However, a few libraries (`struct` and `cmsgpack`) are not included by default. If you are interested
+   in contributing these, check out [this issue](https://github.com/microsoft/garnet/issues/722). Note however, that Lua scripts are slow in general,
+   and if performance and scalability are important, you should instead use our server-side [extensibility](../extensions/overview.md) mechanisms instead.
 4. Garnet respects the FIFO ordering of request-responses. However, when used with larger-than-memory data, and if you
 _opt in_ to using the scatter-gather version of IO (using the `EnableScatterGatherGet [--sg-get]` option) for increased disk performance, then
 even though results are still returned in FIFO order, the read operations may be executed out-of-order to earlier