Adding placeholder for CXL docs

Author: danjoa

cds/cxl.md

@@ -0,0 +1,12 @@
+---
+status: released
+---
+
+# CDS Expression Language (CXL) <UnderConstruction />
+
+This document provides an overview of the CDS Expression Language (CXL) used in CDS models and queries.
+CXL is essentially a standard subset of SQL expressions enhanced by [Path Expressions](../cds/cql#path-expressions) with [Infix Filters](../cds/cql#with-infix-filters).
+
+The documentation is still **under construction** and will be released soon. 
+
+For the time being, please refer to the existing reference docs about [CDS Query Language (CQL)](../cds/cql), and to the [CDS Expression Notation (CXN)](../cds/cxn) documentation.

menu.md

@@ -127,7 +127,8 @@
 ## [Schema Notation (CSN)](cds/csn)
 ## [Query Language (CQL)](cds/cql)
 ## [Query Notation (CQN)](cds/cqn)
-## [Expressions (CXN)](cds/cxn)
+## [Expression Language (CXL)](cds/cxl)
+## [Expression Notation (CXN)](cds/cxn)
 ## [Core / Built-in Types](cds/types)
 ## [Common Reuse Types](cds/common)
 ## [Common Annotations](cds/annotations)