escape a literal asterisk in the platform compatibility tag section

Daniel D. Beck · Daniel D. Beck · commit 309404b30c4e · 2016-02-12T21:25:28.000Z
The unescaped asterisk causes a warning when building the docs and has
unintended formatting consequences.
diff --git a/source/specifications.rst b/source/specifications.rst
@@ -91,7 +91,7 @@ The platform compatibility tagging model used for ``wheel`` distribution is
 defined in :pep:`425`.
 
 The scheme defined in that PEP is insufficient for public distribution
-of Linux wheel files (and *nix wheel files in general), so :pep:`513` was
+of Linux wheel files (and \*nix wheel files in general), so :pep:`513` was
 created to define the ``manylinux1`` tag.
 
 Recording Installed Distributions
