v2.3.2 docs: Link to corresponding v3 docs pages (instead of v3 homepage) where possible

Closes #16277.

2.3.2/base-css.html

@@ -91,7 +91,7 @@
   <div class="container">
 
     <div class="alert alert-danger bs-alert-old-docs">
-      <strong>Heads up!</strong> These docs are for v2.3.2, which is no longer officially supported. <a href="http://getbootstrap.com">Check out the latest version of Bootstrap!</a>
+      <strong>Heads up!</strong> These docs are for v2.3.2, which is no longer officially supported. <a href="http://getbootstrap.com/css/">Check out the latest version of Bootstrap!</a>
     </div>
 
     <!-- Docs nav

2.3.2/components.html

@@ -91,7 +91,7 @@
   <div class="container">
 
     <div class="alert alert-danger bs-alert-old-docs">
-      <strong>Heads up!</strong> These docs are for v2.3.2, which is no longer officially supported. <a href="http://getbootstrap.com">Check out the latest version of Bootstrap!</a>
+      <strong>Heads up!</strong> These docs are for v2.3.2, which is no longer officially supported. <a href="http://getbootstrap.com/components/">Check out the latest version of Bootstrap!</a>
     </div>
 
     <!-- Docs nav

2.3.2/customize.html

@@ -91,7 +91,7 @@
   <div class="container">
 
     <div class="alert alert-danger bs-alert-old-docs">
-      <strong>Heads up!</strong> This was the customizer for Bootstrap v2.3.2, which is no longer officially supported. <a href="http://getbootstrap.com">Check out the latest version of Bootstrap!</a>
+      <strong>Heads up!</strong> This was the customizer for Bootstrap v2.3.2, which is no longer officially supported. <a href="http://getbootstrap.com/customize/">Check out the latest version of Bootstrap!</a>
     </div>
 
     <!-- Docs nav

2.3.2/getting-started.html

@@ -91,7 +91,7 @@
   <div class="container">
 
     <div class="alert alert-danger bs-alert-old-docs">
-      <strong>Heads up!</strong> These docs are for v2.3.2, which is no longer officially supported. <a href="http://getbootstrap.com">Check out the latest version of Bootstrap!</a>
+      <strong>Heads up!</strong> These docs are for v2.3.2, which is no longer officially supported. <a href="http://getbootstrap.com/getting-started/">Check out the latest version of Bootstrap!</a>
     </div>
 
     <!-- Docs nav

2.3.2/javascript.html

@@ -90,7 +90,7 @@
   <div class="container">
 
     <div class="alert alert-danger bs-alert-old-docs">
-      <strong>Heads up!</strong> These docs are for v2.3.2, which is no longer officially supported. <a href="http://getbootstrap.com">Check out the latest version of Bootstrap!</a>
+      <strong>Heads up!</strong> These docs are for v2.3.2, which is no longer officially supported. <a href="http://getbootstrap.com/javascript/">Check out the latest version of Bootstrap!</a>
     </div>
 
     <!-- Docs nav

2.3.2/scaffolding.html

@@ -90,7 +90,7 @@
   <div class="container">
 
     <div class="alert alert-danger bs-alert-old-docs">
-      <strong>Heads up!</strong> These docs are for v2.3.2, which is no longer officially supported. <a href="http://getbootstrap.com">Check out the latest version of Bootstrap!</a>
+      <strong>Heads up!</strong> These docs are for v2.3.2, which is no longer officially supported. <a href="http://getbootstrap.com/css/">Check out the latest version of Bootstrap!</a>
     </div>
 
     <!-- Docs nav