update manual to talk about a %section's -[opu] options

openpkg/rc.pod

@@ -161,6 +161,20 @@ There are 9 sections which have no special meaning to the B<rc> program,
 but are used in B<OpenPKG> by convention for standard purposes. Hence,
 do not use them for arbitrary things instead.
 
+Throughout these sections it is possible to specify the user to be
+switched to before the code is executed.
+
+A priority can be given for each snippet to control execution sequence
+when "all" packages are given. Higher priority leads to early start and
+late stop. Priority is a number where low numbers mean high priority
+(numeric sort for start). When omitted, the priority defaults to 500.
+
+Output generated to STDOUT and STDERR is captured and normally
+surpressed. In case the scriptlet exits with a nonzero return value the
+intercepted messages are consolidated, reformatted with a surrounding
+ASCII-art border and printed to STDERR. If the section is tagged with -o
+option, STDOUT messages are passed through verbatim.
+
 =over 4
 
 =item C<%start> [B<-u> I<user>] [B<-p> I<priority>]