Update 'auth_strength' definition in spec.md

Clarified the definition of 'auth_strength' and its components.

Author: char0n

docs/specification/spec.md

@@ -732,10 +732,13 @@ It evaluates the average strength of all security schemes using normative scores
 auth_strength = sum(strength_scores) / schemes_count
 ```
 
-Where
+
+Where:
 - `strength_scores` is the list of calculated scheme strengths
 - `schemes_count` is the number of defined schemes
 
+
+
 The following table outlines the `auth_strength` scoring weights:
 
 | Scheme Type | Description | Example | Strength | Rationale |