Updated Coding style policy (markdown)

Coding-style-policy.md

@@ -15,6 +15,18 @@ RSS-Bridge uses tabs for indentation on all PHP files in the repository (except
 
 _Reference_: [`Generic.WhiteSpace.DisallowSpaceIndent`](https://github.com/squizlabs/PHP_CodeSniffer/blob/master/src/Standards/Generic/Sniffs/WhiteSpace/DisallowSpaceIndentSniff.php)
 
+# Add spaces around the concatenation operator
+
+The concatenation operator should have one space on both sides in order to improve readability.
+
+
+  <rule ref="Squiz.Strings.ConcatenationSpacing">
+    <properties>
+      <property name="spacing" value="1"/>
+      <property name="ignoreNewlines" value="true"/>
+    </properties>
+  </rule>
+
 # Maximum line length
 
 One line of code should have no more than **80 characters** (soft limit) and must never exceed **120 characters** (hard limit).