docs: Add language support Matrix (#920)

Author: kyleconroy

docs/index.rst

@@ -61,6 +61,7 @@ code ever again.
    reference/config.md
    reference/datatypes.md
    reference/query-annotations.md
+   reference/language-support.rst
 
 .. toctree::
    :maxdepth: 2

docs/reference/language-support.rst

@@ -0,0 +1,20 @@
+Database and Language Support
+#############################
+
+========  ======  ==========
+Language  MySQL   PostgreSQL
+--------  ------  ----------
+Go        Stable  Stable
+Kotlin    Beta    Beta
+========  ======  ==========
+
+Planned Language Support
+************************
+
+- `C# <https://github.com/kyleconroy/sqlc/issues/373>`_
+- `TypeScript <https://github.com/kyleconroy/sqlc/issues/296>`_
+
+Planned Database Support
+************************
+
+- `SQLite <https://github.com/kyleconroy/sqlc/issues/161>`_