[Doc] Cover all errors of PEAR ClassDeclaration

While reviewing PR PHPCSStandards#844 for the Squiz version of this sniff, jrfnl
discovered that the PEAR sniff's documentation did not cover all error
conditions.

This adds code examples for all missing errors that should be caught by
this sniff.

Author: braindawg

src/Standards/PEAR/Docs/Classes/ClassDeclarationStandard.xml

@@ -19,4 +19,78 @@ class Foo <em>{</em>
         ]]>
         </code>
     </code_comparison>
+    <code_comparison>
+        <code title="Valid: Opening brace on the correct line.">
+        <![CDATA[
+class Foo
+<em>{</em>
+}
+        ]]>
+        </code>
+        <code title="Invalid: Newline between declaration and opening brace.">
+        <![CDATA[
+class Foo
+<em></em>
+{
+}
+        ]]>
+        </code>
+    </code_comparison>
+    <code_comparison>
+        <code title="Valid: Opening brace is on a line by itself.">
+        <![CDATA[
+class Foo
+<em>{</em>
+}
+        ]]>
+        </code>
+        <code title="Invalid: Opening brace is not alone on its line.">
+        <![CDATA[
+class Foo
+{<em> public function __construct() {}</em>
+}
+        ]]>
+        </code>
+    </code_comparison>
+    <standard>
+    <![CDATA[
+    The opening brace must be indented to the same depth as the class declaration.
+    ]]>
+    </standard>
+    <code_comparison>
+        <code title="Valid: Opening brace indentation depth matches the class definition.">
+        <![CDATA[
+if (!class_exists('Foo')) {
+    abstract class Foo
+    <em>{</em>
+    }
+}
+        ]]>
+        </code>
+        <code title="Invalid: Expected 4 spaces before opening brace; 0 found.">
+        <![CDATA[
+if (!class_exists('Foo')) {
+    abstract class Foo
+<em>{</em>
+}
+}
+        ]]>
+        </code>
+    </code_comparison>
+    <code_comparison>
+        <code title="Valid: Opening brace indentation depth matches the class definition.">
+        <![CDATA[
+class Foo
+<em>{</em>
+}
+        ]]>
+        </code>
+        <code title="Invalid: Expected 0 spaces before opening brace; 4 found.">
+        <![CDATA[
+class Foo
+    <em>{</em>
+    }
+        ]]>
+        </code>
+    </code_comparison>
 </documentation>