Merge branch 'master' into gh-pages

.gitignore

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+_site
+.sass-cache
+.jekyll-cache
+.jekyll-metadata
+vendor
+.DS_Store

index.html

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             <p>So I wanted to write an understandable and concise guide. One that would cover all the certification objectives. One that would cut all the fluff and that would explain in simple terms hard concepts. One that is easy to read. One that would be accessible to anyone willing to learn.</p>
             <p>And here is it. </p>
-            <p>Are you interested in one of the Java 8 upgrade exams (1Z0-810 or 1Z0-813)?<br/>This book can also help you! See this <a href="upgrade.html">page</a>.</p>
-            <p>If you read it and like it, can you buy a copy so I can keep creating free content?</p>
+            <p>Are you interested in the Java 17 certification exam (1Z0-829)?<br/>I have a <a href="https://ocpj17.javastudyguide.com">guide for this exam</a>.</p>
+            <p>Are you interested in the Java 21 certification exam (1Z0-830)?<br/>I have a <a href="https://ocpj21.javastudyguide.com">guide for this exam</a>.</p>
+            <p>If you read this guide for Java 8 and like it, can you buy a copy so I can keep creating free content?</p>
             <div class="buy-info"></div>
             <p>This site is on <a href="https://github.com/eh3rrera/ocpj8-book">Github</a>, so you can fork it, modify it, and create pull requests.</p>