doc: Add trivia macro

Useful for random historical facts that give useful context for developers
of Liza.  It hopefully helps to mitigate some of the issues of Theory
Building as noted by Peter Naur.

* doc/liza.css: Refactor some styles to make them more concise.
  (.trivia): Add styling.
* doc/macros.texi (trivia): Add macro.

doc/liza.css

@@ -125,9 +125,7 @@ but don't sacrifice space on small screens.
     border-color: #d33682;
 }
 
-.doc-notice.devnotice p::before,
-.doc-notice.devnote p::before,
-.doc-notice.tip p::before
+.doc-notice p::before
 {
     display: block;
     float: left;
@@ -151,9 +149,12 @@ but don't sacrifice space on small screens.
     content: '\261E';
 }
 
-.doc-notice.devnotice p,
-.doc-notice.devnote p,
-.doc-notice.tip p
+.doc-notice.trivia p::before
+{
+    content: '\1F914';
+}
+
+.doc-notice p
 {
     padding-left: 1.75em;
 }

doc/macros.texi

@@ -150,6 +150,18 @@ This system has maintenance concerns.
 @end macro
 
 
+@c Conveying the historical details of the project is important to
+@c understand why the system exists in the state that it does
+@c today.  Use of this macro will hopefully help mitigate some of the
+@c problems noted by Peter Naur in his paper Programming as Theory Building:
+@c   http://pages.cs.wisc.edu/~remzi/Naur.pdf
+@macro trivia{text}
+@noticestart{trivia}
+\text\
+@noticeend
+@end macro
+
+
 @c link to source file if URI is known, otherwise display
 @c the path to the file
 @ifset SRCURI