Fix unterminated asciidoc blocks

Author: per1234

Language/Functions/USB/Keyboard/keyboardBegin.adoc

@@ -67,4 +67,5 @@ void loop() {
 }
 ----
 
+--
 // HOW TO USE SECTION ENDS

Language/Functions/USB/Keyboard/keyboardModifiers.adoc

@@ -64,6 +64,7 @@ The Leonardo's definitions for modifier keys are listed below:
 |KEY_F10	|0xCB	|203
 |KEY_F11	|0xCC	|204
 |KEY_F12	|0xCD	|205
+|===
 
 --
 // OVERVIEW SECTION ENDS

Language/Variables/Data Types/String/Functions/reserve.adoc

@@ -70,6 +70,7 @@ void loop() {
   // nothing to do here
 }
 ----
+--
 // HOW TO USE SECTION ENDS