Created Calling functions (markdown)

Calling-functions.md

@@ -0,0 +1,93 @@
+Function calls must follow a few rules in order to maintain readability throughout the project:
+
+**Do not add whitespace before the opening parenthesis**
+
+<details><summary>Example</summary><div><br>
+
+**Bad**
+
+```PHP
+$result = my_function ($param);
+```
+
+**Good**
+
+```PHP
+$result = my_function($param);
+```
+
+</div></details><br>
+
+**Do not add whitespace after the opening parenthesis**
+
+<details><summary>Example</summary><div><br>
+
+**Bad**
+
+```PHP
+$result = my_function( $param);
+```
+
+**Good**
+
+```PHP
+$result = my_function($param);
+```
+
+</div></details><br>
+
+**Do not add a space before the closing parenthesis**
+
+<details><summary>Example</summary><div><br>
+
+**Bad**
+
+```PHP
+$result = my_function($param );
+```
+
+**Good**
+
+```PHP
+$result = my_function($param);
+```
+
+</div></details><br>
+
+**Do not add a space before a comma**
+
+<details><summary>Example</summary><div><br>
+
+**Bad**
+
+```PHP
+$result = my_function($param1 ,$param2);
+```
+
+**Good**
+
+```PHP
+$result = my_function($param1, $param2);
+```
+
+</div></details><br>
+
+**Add a space after a comma**
+
+<details><summary>Example</summary><div><br>
+
+**Bad**
+
+```PHP
+$result = my_function($param1,$param2);
+```
+
+**Good**
+
+```PHP
+$result = my_function($param1, $param2);
+```
+
+</div></details><br>
+
+_Reference_: [`Generic.Functions.FunctionCallArgumentSpacing`](https://github.com/squizlabs/PHP_CodeSniffer/blob/master/src/Standards/Generic/Sniffs/Functions/FunctionCallArgumentSpacingSniff.php)