[SYCL] [L0] Adding a new environment variable to documentation

Signed-off-by: Arvind Sudarsanam <[email protected]>

Author: asudarsa

sycl/doc/EnvironmentVariables.md

@@ -32,6 +32,7 @@ subject to change. Do not rely on these variables in production code.
 | SYCL_PARALLEL_FOR_RANGE_ROUNDING_TRACE | Any(\*) | Enables tracing of parallel_for invocations with rounded-up ranges. |
 | SYCL_DISABLE_PARALLEL_FOR_RANGE_ROUNDING | Any(\*) | Disables automatic rounding-up of parallel_for invocation ranges. |
 | SYCL_ENABLE_PCI | Integer | When set to 1, enables obtaining the GPU PCI address when using the Level Zero backend. The default is 0. |
+| SYCL_PI_LEVEL_ZERO_FILTER_EVENT_WAIT_LIST | Integer | When set to 0, disables filtering of signaled events from wait lists when using the Level Zero backend. The default is 1. |
 
 `(*) Note: Any means this environment variable is effective when set to any non-null value.`