add caveats to man page

templates/manpage_template

@@ -96,6 +96,19 @@ Local plugin filenames must be valid python module names, therefore must consist
 
 Note: The application data directory follows the XDG Base Directory Specification
 
+.SH CAVEATS
+\fBLocale:\fP For best results set the \fBLANG\fP locale environment variable to \fBC\fP. For example, either by setting directly on the command-line:
+
+\fB$ LANG=C date | jc --date\fP
+
+or by exporting to the environment before running commands:
+
+\fB$ export LANG=C\fP
+
+\fBTimezones:\fP Some parsers have calculated epoch timestamp fields added to the output. Unless a timestamp field name has a \fB_utc\fP suffix it is considered naive. (i.e. based on the local timezone of the system the \fBjc\fP parser was run on).
+
+If a UTC timezone can be detected in the text of the command output, the timestamp will be timezone aware and have a \fB_utc\fP suffix on the key name. (e.g. \fBepoch_utc\fP) No other timezones are supported for aware timestamps.
+
 .SH EXAMPLES
 Standard Syntax:
 .RS