docs(conditionals): added preference for positive boolean expressions and reduced strength of ternary recommendation.

Author: Manason

docs/conditionals.md

@@ -1,7 +1,7 @@
 # Conditionals
 
 ## Default Values
-Use [ternary operator](http://lua-users.org/wiki/TernaryOperator) 'or' Instead of nil checks for performance and readability optimization.
+Consider [ternary operator](http://lua-users.org/wiki/TernaryOperator) 'or' instead of nil checks to improve readability.
 ```lua title="BAD"
 if name then
     return name
@@ -25,3 +25,20 @@ end
 ```lua title="GOOD"
 return name == "mark" or name == "stacy"
 ```
+
+## Prefer positive boolean expressions
+This makes the code easier to read.
+```lua title="BAD"
+if not isHappy then
+  return "sad"
+else
+  return "happy"
+end
+```
+```lua title="GOOD"
+if isHappy then
+  return "happy"
+else
+  return "sad"
+end
+```