Small typos. Added section about nested expressions inside format specifiers.

pep-0498.txt

@@ -229,7 +229,17 @@ Is equivalent to::
 Format specifiers
 -----------------
 
-Format specifiers are not interpreted by the f-string parser. Just as
+Format specifiers may also contain evaluated expressions. This allows
+code such as::
+
+  >>> width = 10
+  >>> precision = 4
+  >>> value = decimal.Decimal('12.34567')
+  >>> f'result: {value:{width}.{prevision}}'
+  'result:      12.35'
+
+Once expressions in a format specifier are evaluated (if necessary),
+format specifiers are not interpreted by the f-string evaluator. Just as
 in str.format(), they are merely passed in to the __format__() method
 of the object being formatted.
 
@@ -325,7 +335,7 @@ Discussion
 Most of the discussions on python-ideas [#]_ focused on a few issues:
 
  - Whether to allow full Python expressions.
- - How to designate f-strings, and how specify the locaton of
+ - How to designate f-strings, and how to specify the location of
    expressions in them.
  - How to concatenate adjacent strings and f-strings.