[12.x] Add support for Redis Unix socket connections with PhpRedis (#10306)

* Update redis, add Unix socket instructions

Add Unix socket configuration instructions for Redis

* Update redis.md

---------

Co-authored-by: Taylor Otwell <[email protected]>

Author: dansleboby

Diff for: redis.md

@@ -210,6 +210,16 @@ In addition to the default configuration options, PhpRedis supports the followin
 ],
 ```
 
+<a name="unix-socket-connections"></a>
+#### Unix Socket Connections
+
+Redis connections can also be configured to use Unix sockets instead of TCP. This can offer improved performance by eliminating TCP overhead for connections to Redis instances on the same server as your application. To configure Redis to use a Unix socket, set your `REDIS_HOST` environment variable to the path of the Redis socket and the `REDIS_PORT` environment variable to `0`:
+
+```env
+REDIS_HOST=/run/redis/redis.sock
+REDIS_PORT=0
+```
+
 <a name="phpredis-serialization"></a>
 #### PhpRedis Serialization and Compression