Add helper text for log path.

conf/locale/locale_en-US.ini

@@ -87,6 +87,7 @@ http_port_helper = Port number which application will listen on.
 app_url = Application URL
 app_url_helper = This affects HTTP/HTTPS clone URL and somewhere in email.
 log_root_path = Log Path
+log_root_path_helper = Directory to write log files to.
 
 optional_title = Optional Settings
 email_title = Email Service Settings

templates/install.tmpl

@@ -112,6 +112,7 @@
 					<div class="inline required field">
 						<label for="log_root_path">{{.i18n.Tr "install.log_root_path"}}</label>
 						<input id="log_root_path" name="log_root_path" value="{{.log_root_path}}" placeholder="log" required>
+						<span class="help">{{.i18n.Tr "install.log_root_path_helper"}}</span>
 					</div>