[fidl][docs] Remove obsolete protocol declaration examples

Since the adoption of FTP-024, the inheritance syntax for protocol
declarations is no longer supported. Remove examples which use it.

Note: the spec already has examples of the new syntax, so no need
to add those here.

Change-Id: Ieb106b8d5f57026d0f766371ca174447f60af9ab
diff --git a/docs/development/languages/fidl/reference/language.md b/docs/development/languages/fidl/reference/language.md
index b30dfc5..cbce7f7a 100644
--- a/docs/development/languages/fidl/reference/language.md
+++ b/docs/development/languages/fidl/reference/language.md
@@ -639,21 +639,6 @@
     Clear();
     -> OnClear();
 };
-
-protocol RealCalculator : Calculator {
-    AddFloats(float32 a, float32 b) -> (float32 sum);
-};
-
-protocol Science {
-    Hypothesize();
-    Investigate();
-    Explode();
-    Reproduce();
-};
-
-protocol ScientificCalculator : RealCalculator, Science {
-    Sin(float32 x) -> (float32 result);
-};
 ```
 
 #### Use