Add the documentation for the PSR12 Boolean Operator Placement sniff

Co-authored-by: Juliette <[email protected]>

Author: dingo-d

src/Standards/PSR12/Docs/ControlStructures/BooleanOperatorPlacementStandard.xml

@@ -0,0 +1,59 @@
+<documentation title="Boolean Operator Placement">
+    <standard>
+    <![CDATA[
+    Boolean operators between conditions in control structures must always be at the beginning or at the end of the line, not a mix of both.
+
+    This rule applies to if/else conditions, while loops and switch/match statements.
+    ]]>
+    </standard>
+    <code_comparison>
+        <code title="Valid: Boolean operator between conditions consistently at the beginning of the line.">
+        <![CDATA[
+if (
+    $expr1
+    && $expr2
+    && ($expr3
+    || $expr4)
+    && $expr5
+) {
+    // if body.
+}
+        ]]>
+        </code>
+        <code title="Invalid: Mix of boolean operators at the beginning and the end of the line.">
+        <![CDATA[
+if (
+    $expr1 &&
+    ($expr2 || $expr3)
+    && $expr4
+) {
+    // if body.
+}
+        ]]>
+        </code>
+    </code_comparison>
+    <code_comparison>
+        <code title="Valid: Boolean operator between conditions consistently at the end of the line.">
+        <![CDATA[
+if (
+    $expr1 ||
+    ($expr2 || $expr3) &&
+    $expr4
+) {
+    // if body.
+}
+        ]]>
+        </code>
+        <code title="Invalid: Mix of boolean operators at the beginning and the end of the line.">
+        <![CDATA[
+match (
+    $expr1
+    && $expr2 ||
+    $expr3
+) {
+    // structure body.
+};
+        ]]>
+        </code>
+    </code_comparison>
+</documentation>