[PATCH] Improved readability of the operator documentation

[Johannes Erwerle]

Hi!

Every now and then I have to look up what the ~ operator does exactly.
Finding the right combination of types in the long running text is always quite hard.
I think that formatting that as a list would make this easier.

I also put different kinds of operators into different paragraphs,
because I think this also makes it easier to find what you are looking for in this section.

For reference: This is the block I am talking about:
https://bird.network.cz/?get_doc&v=20&f=bird-5.html#ss5.3

Kind Regards
Jo

 From 08c1e50a97b0afd6522d52ba0f9488c8cc3cb9f8 Mon Sep 17 00:00:00 2001
From: Johannes Erwerle <jo at swagspace.org>
Date: Sat, 12 Oct 2024 09:07:42 +0200
Subject: [PATCH] Improved readability of the operator documentation

---
  doc/bird.sgml | 40 +++++++++++++++++++++++++---------------
  1 file changed, 25 insertions(+), 15 deletions(-)

diff --git a/doc/bird.sgml b/doc/bird.sgml
index 6857452d..7ee066bb 100644
--- a/doc/bird.sgml
+++ b/doc/bird.sgml
@@ -1897,21 +1897,31 @@ in the foot).
  <label id="operators">
  
  <p>The filter language supports common integer operators <cf>(+,-,*,/)</cf>,
-parentheses <cf/(a*(b+c))/, comparison <cf/(a=b, a!=b, a<b, a>=b)/.
-Logical operations include unary not (<cf/!/), and (<cf/&&/), and or
-(<cf/||/). Special operators include (<cf/˜/,
-<cf/!˜/) for "is (not) element of a set" operation - it can be used on
-element and set of elements of the same type (returning true if element is
-contained in the given set), or on two strings (returning true if first string
-matches a shell-like pattern stored in second string) or on IP and prefix
-(returning true if IP is within the range defined by that prefix), or on prefix
-and prefix (returning true if first prefix is more specific than second one) or
-on bgppath and bgpmask (returning true if the path matches the mask) or on
-number and bgppath (returning true if the number is in the path) or on bgppath
-and int (number) set (returning true if any ASN from the path is in the set) or
-on pair/quad and clist (returning true if the pair/quad is element of the
-clist) or on clist and pair/quad set (returning true if there is an element of
-the clist that is also a member of the pair/quad set).
+parentheses <cf/(a*(b+c))/, comparison <cf/(a=b, a!=b, a<b, a>=b)/.</p>
+
+<p>Logical operations include unary not (<cf/!/), and (<cf/&&/), and or
+(<cf/||/).</p>
+
+<p>Special operators include (<cf/˜/,
+<cf/!˜/) for "is (not) element of a set" operation - it can be used on:
+<itemize>
+  <item>element and set of elements of the same type (returning true if
+    element is contained in the given set)
+  <item>two strings (returning true if first string matches a shell-like
+    pattern stored in second string)
+  <item>IP and prefix (returning true if IP is within the range defined by
+    that prefix),
+  <item>prefix and prefix (returning true if first prefix is more specific
+    than second one)
+  <item>bgppath and bgpmask (returning true if the path matches the mask)
+  <item>number and bgppath (returning true if the number is in the path)
+  <item>bgppath and int (number) set (returning true if any ASN from the
+    path is in the set)
+  <item>pair/quad and clist (returning true if the pair/quad is element of
+    the clist)
+  <item>clist and pair/quad set (returning true if there is an element of the
+    clist that is also a member of the pair/quad set).
+</itemize>
  
  <p>There is one operator related to ROA infrastructure - <cf/roa_check()/. It
  examines a ROA table and does <rfc id="6483"> route origin validation for a
-- 
2.46.0