Apply suggestions from code review

Co-Authored-By: Trishank K Kuppusamy <[email protected]>

pep-0458.txt

@@ -340,8 +340,8 @@ delegated to by *bins* (i.e., *bin-n*).  The *timestamp* and *snapshot*
 metadata MUST be updated whenever *root*, *targets* or delegated metadata are
 updated.  Observe, though, that *root* and *targets* metadata are much less
 likely to be updated as often as delegated metadata.  Similarly, the *bins* role
-will only be updated when new bins are added.  Therefore, *timestamp*
-and *snapshot* metadata will most likely be updated frequently (possibly every
+will only be updated when new bins are added.  Therefore, *timestamp*,
+*snapshot*, and *bin-n* metadata will most likely be updated frequently (possibly every
 minute) due to delegated metadata being updated frequently in order to support
 continuous delivery of projects.  Continuous delivery is a set of processes
 that PyPI uses produce snapshots that can safely coexist and be deleted
@@ -413,10 +413,10 @@ PyPI.
 Metadata Expiry Times
 ---------------------
 
-The *root* and *targets* role metadata SHOULD expire in one year, because these
+The metadata for the *root*, *targets*, and *bins* roles SHOULD each expire in one year, because these
 two metadata files are expected to change very rarely.
 
-The *timestamp*, *snapshot*, and *bin-n* metadata SHOULD expire in one day
+The *timestamp*, *snapshot*, and *bin-n* metadata SHOULD each expire in one day
 because a CDN or mirror SHOULD synchronize itself with PyPI every day.
 Furthermore, this generous time frame also takes into account client clocks
 that are highly skewed or adrift.