Update title and descriptions for manual pages

This makes use of the new information that Phd will display once
php/phd#201 is merged.

It changes the title on the home page also to just "PHP" (removing the `:
Hypertext Preprocessor` part).

It also changes the meta information for manual pages, which is used for social
media cards.

Author: derickr

include/header.inc

@@ -65,7 +65,7 @@ if (!isset($config["languages"])) {
    <base href="<?php echo $_SERVER["BASE_HREF"]; ?>">
   <?php endif ?>
 
-  <title>PHP: <?php echo $title ?></title>
+  <title><?php echo $title ?></title>
 
   <?php foreach($CSS as $filename => $modified): ?>
     <link rel="stylesheet" type="text/css" href="/cached.php?t=<?php echo $modified?>&amp;f=<?php echo $filename?>" media="screen">

include/layout.inc

@@ -421,12 +421,13 @@ EOT;
     return $retval;
 }
 
-function site_header(string $title = 'Hypertext Preprocessor', array $config = []): void
+function site_header(?string $title = NULL, array $config = []): void
 {
     global $MYSITE, $LANG;
 
+    $title = $title ? "PHP: {$title}" : 'PHP';
     $meta_image_path = $MYSITE . 'images/meta-image.png';
-    $meta_description = "PHP is a popular general-purpose scripting language that powers everything from your blog to the most popular websites in the world.";
+    $meta_description = $config['description'] ?? $title;
 
     $defaults = [
         "lang" => $LANG,
@@ -441,13 +442,13 @@ function site_header(string $title = 'Hypertext Preprocessor', array $config = [
 
 <meta name="twitter:card" content="summary_large_image" />
 <meta name="twitter:site" content="@official_php" />
-<meta name="twitter:title" content="PHP: Hypertext Preprocessor" />
+<meta name="twitter:title" content="{$title}" />
 <meta name="twitter:description" content="{$meta_description}" />
 <meta name="twitter:creator" content="@official_php" />
 <meta name="twitter:image:src" content="{$meta_image_path}" />
 
-<meta itemprop="name" content="PHP: Hypertext Preprocessor" />
-<meta itemprop="description" content="$meta_description" />
+<meta itemprop="name" content="{$title}" />
+<meta itemprop="description" content="{$meta_description}" />
 <meta itemprop="image" content="{$meta_image_path}" />
 
 <meta property="og:image" content="{$meta_image_path}" />

include/shared-manual.inc

@@ -325,6 +325,7 @@ function manual_setup($setup): void {
         "prev" => $setup["prev"],
         "next" => $setup["next"],
         "cache" => $lastmod,
+        "description" => $setup["this"][2] ?? null,
     ];
     site_header($setup["this"][1] . " - Manual ", $config);
 

index.php

@@ -108,7 +108,7 @@
   </div>
 EOF;
 
-site_header("Hypertext Preprocessor",
+site_header(NULL,
     [
         'current' => 'home',
         'headtags' => [