Wording in Error Message Style Guide - Mailing list pgsql-docs

Perhaps a nitpick, but in subsection 51.3.1 in the "Error Message Style Guide"
the language in the rationale for avoiding implementation details seems to not
be in line with the overall one of voice of the docs.  ISTM the following reads
better:

-    don't know the details anyway.
+    aren't expected to know the details.

Patch attached.

cheers ./daniel