'make doc' is not deterministic due to "v=..." tokens/ids in stylesheet links

[apjanke]

Whenever you make doc (which happens as part of make dist), you get spurious diffs in several of the HTML files. This prevents idempotent/deterministic builds.

diff --git a/doc/examples/AnimatedPlots.html b/doc/examples/AnimatedPlots.html
index c346b40..79e6ad8 100644
--- a/doc/examples/AnimatedPlots.html
+++ b/doc/examples/AnimatedPlots.html
@@ -24,7 +24,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1">
     <meta name="theme-color" content="#157878">
     <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
-    <link rel="stylesheet" href="/assets/css/style.css?v=d4c108392921baf2082c96659e81becd933cb76d">
+    <link rel="stylesheet" href="/assets/css/style.css?v=7b58e49f07a8bb92bf06b99d687a4498f473bb8a">
     <!-- start custom head snippets, customize with your own _includes/head-custom.html file -->

 <!-- Setup Google Analytics -->
diff --git a/doc/examples/broken/symbolicMathExample.html b/doc/examples/broken/symbolicMathExample.html
index 70a8322..64677db 100644
--- a/doc/examples/broken/symbolicMathExample.html
+++ b/doc/examples/broken/symbolicMathExample.html
@@ -24,7 +24,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1">
     <meta name="theme-color" content="#157878">
     <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
-    <link rel="stylesheet" href="/assets/css/style.css?v=d4c108392921baf2082c96659e81becd933cb76d">
+    <link rel="stylesheet" href="/assets/css/style.css?v=7b58e49f07a8bb92bf06b99d687a4498f473bb8a">
     <!-- start custom head snippets, customize with your own _includes/head-custom.html file -->