links in importlib.metadata.rst replaced with sphinx references (GH-17730)

The importlib.metadata documentation uses hardcoded links to internal
pages. This results in minor rendering issues. This change replaces
the hardcoded links with suitable Sphinx roles.

Signed-off-by: Oleg Höfling <oleg.hoefling@gmail.com>
diff --git a/Misc/ACKS b/Misc/ACKS
index 8ab7a6c..5ecbac1 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -751,6 +751,7 @@
 Gerhard Häring
 Fredrik Håård
 Florian Höch
+Oleg Höfling
 Robert Hölzl
 Catalin Iacob
 Mihai Ibanescu