Remove no-op FRR512 from feafure file

This constraint was being used for testing on a development branch, but not meant to be merged in intentionally with #1225.

Author: aj-stein-gsa

features/fedramp_extensions.feature

@@ -211,7 +211,6 @@ Examples:
   | frr305 |
   | frr306 |
   | frr307 |
-  | frr512 |
 #END_DYNAMIC_CONSTRAINT_IDS
 
 @constraints
@@ -605,4 +604,4 @@ Examples:
 
 @style-guide
 Scenario: Validating content line length constraints
-  Then I should verify that all invalid sample content is smaller than 100 lines
+  Then I should verify that all invalid sample content is smaller than 100 lines