[libc++][format] Enables feature-test macro.
The macro is only enabled when the Clang is used with
-fexperimental-library.
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D130792
NOKEYCHECK=True
GitOrigin-RevId: 679169b7dd74c6f9161353f07e716ec25e80d1b8
diff --git a/docs/FeatureTestMacroTable.rst b/docs/FeatureTestMacroTable.rst
index 7ab2d6c..9aa183a 100644
--- a/docs/FeatureTestMacroTable.rst
+++ b/docs/FeatureTestMacroTable.rst
@@ -234,7 +234,7 @@
------------------------------------------------- -----------------
``__cpp_lib_execution`` *unimplemented*
------------------------------------------------- -----------------
- ``__cpp_lib_format`` *unimplemented*
+ ``__cpp_lib_format`` ``202106L``
------------------------------------------------- -----------------
``__cpp_lib_generic_unordered_lookup`` ``201811L``
------------------------------------------------- -----------------