Sync docs from master to gh-pages

reference/html/advanced.html

@@ -780,6 +780,7 @@ public interface SingleTestGenerator {
      * or {@code .php}
      * @param properties - properties passed to the plugin
      */
+    @Deprecated
     String fileExtension(ContractVerifierConfigProperties properties);
 
     class GeneratedClassData {

reference/html/gradle-project.html

@@ -699,7 +699,7 @@ The following example shows how it works in the <code>contracts</code> closure:<
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-<pre class="highlightjs highlight"><code class="language-groovy hljs" data-lang="groovy">packageWithBaseClasses = 'com.example.base'</code></pre>
+<pre class="highlightjs highlight"><code class="language-groovy hljs" data-lang="groovy">packageWithBaseClasses.set('com.example.base')</code></pre>
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@@ -717,7 +717,7 @@ name of the base class for the matched contract. You have to provide a list call
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-<pre class="highlightjs highlight"><code class="language-groovy hljs" data-lang="groovy">baseClassForTests = "com.example.FooBase"
+<pre class="highlightjs highlight"><code class="language-groovy hljs" data-lang="groovy">baseClassForTests.set("com.example.FooBase")
 baseClassMappings {
     baseClassMapping('.*/com/.*', 'com.example.ComBase')
     baseClassMapping('.*/bar/.*': 'com.example.BarBase')