docs(readme) elaborate on new 'peek()' remaining ttl return value

README.md

@@ -745,8 +745,12 @@ If there is no value for the queried `key`, it returns `nil` and no error.
 If there is a value for the queried `key`, it returns a number indicating the
 remaining TTL of the cached value (in seconds) and no error. If the value for
 `key` has expired but is still in the L2 cache, returned TTL value will be
-negative. Finally, the third returned value in that case will be the cached
-value itself, for convenience.
+negative. The remaining TTL return value will only be `0` if the queried `key`
+has an indefinite ttl (`ttl=0`). Otherwise, this return value may be positive
+(`key` still valid), or negative (`key` is stale).
+
+The third returned value will be the cached value as stored in the L2 cache, if
+still available.
 
 This method is useful when you want to determine if a value is cached. A value
 stored in the L2 cache is considered cached regardless of whether or not it is