importlib.resources was added in 3.7 (#5468)

Describe sub-module versioning

stdlib/VERSIONS

@@ -1,6 +1,6 @@
 # The structure of this file is as follows:
 # - Blank lines and lines starting with `#` are ignored.
-# - Lines contain the name of a top-level module, followed by a colon,
+# - Lines contain the name of a module, followed by a colon,
 #   a space, and a version range (for example: `symbol: 2.7-3.9`).
 #
 # Version ranges may be of the form "X.Y-A.B" or "X.Y-". The
@@ -9,6 +9,9 @@
 # introduced in version X.Y and is still available in the latest
 # version of Python.
 #
+# If a submodule is not listed separately, it has the same lifetime as
+# its parent module.
+#
 # Python versions before 2.7 are ignored, so any module that was already
 # present in 2.7 will have "2.7" as its minimum version. Version ranges
 # for unsupported versions of Python 3 (currently 3.5 and lower) are
@@ -132,6 +135,7 @@ imaplib: 2.7-
 imghdr: 2.7-
 imp: 2.7-
 importlib: 2.7-
+importlib.resources: 3.7-
 inspect: 2.7-
 io: 2.7-
 ipaddress: 2.7-