[CMD] Tweak comment for %TIME% format (#5499)

- Precisely describe `time` format, based on CLDR standard:
  http://www.unicode.org/reports/tr35/tr35-dates.html#Date_Field_Symbol_Table
- Had spent time verifying the behavior on Windows and ReactOS,
  this strict definition may be helpful for future researchers.

base/shell/cmd/locale.c

@@ -68,7 +68,7 @@ GetDateString(VOID)
     return szDate;
 }
 
-/* Return time in hh:mm:ss.xx format. Used for $T in prompt and %TIME% */
+/* Return time in H:mm:ss.SS format. Used for $T in prompt and %TIME% */
 LPTSTR
 GetTimeString(VOID)
 {