Add Variable Naming Style Guideline to Common Language Guide. Include…

…d a PHP Example for Good and Bad Examples. (#3)

guides/common.md

@@ -1,6 +1,9 @@
 # Common Language Style Guide
 
+## Capitalization
+
 The following terms describe different forms of capitalization
+
 - StudlyCase
 - camelCase
 - UPPER_CASE
@@ -9,17 +12,42 @@ The following terms describe different forms of capitalization
 
 If an identifier contains more than one word, do not use underscores ( _ ) or hyphens ( - ), except when the identifier is using UPPER_CASE or snake_case.
 
-| Identifier          | Casing      |
-| -----------         | ----------- |
-| Class               | StudlyCase  |
-| Interface           | StudlyCase  |
-| Enum Type           | StudlyCase  |
-| Enum Value          | StudlyCase  |
-| Constants           | UPPER_CASE  |
-| Properties          | camelCase   |
-| Method Parameters   | camelCase   |
-| Methods Names       | camelCase   |
-| Function Name       | snake_case  |
-| Function Parameters | camelCase   |
-
-If you encounter a scenario not covered here, please refer to the language-specific style guide. Please open a PR detailing your proposed solution if the scenario is still not covered.
+| Identifier          | Casing     |
+|---------------------|------------|
+| Class               | StudlyCase |
+| Interface           | StudlyCase |
+| Enum Type           | StudlyCase |
+| Enum Value          | StudlyCase |
+| Constants           | UPPER_CASE |
+| Properties          | camelCase  |
+| Method Parameters   | camelCase  |
+| Methods Names       | camelCase  |
+| Function Name       | snake_case |
+| Function Parameters | camelCase  |
+
+
+## Variable Naming
+
+Variables should always be named descriptively and concisely. Single character variables should never be used unless otherwise specified in a language
+specific style guide.
+
+#### Bad Variable Naming
+
+```php
+foreach ($items as $i) {
+    //do things in the iteration
+}
+```
+
+#### Good Variable Naming
+
+```php
+foreach ($items as $item) {
+    //do things in the iteration
+}
+```
+
+## Other Scenarios
+
+If you encounter a scenario not covered here, please refer to the language-specific style guide. Please open a PR detailing your proposed solution if
+the scenario is still not covered.