Format all instructions.append.md to start with an H1 (required but ignored) and H2

exercises/practice/anagram/.docs/instructions.append.md

@@ -1,3 +1,5 @@
 # Instructions Append
 
+## Implementation
+
 The anagrams can be returned in any order.

exercises/practice/complex-numbers/.docs/instructions.append.md

@@ -1,4 +1,6 @@
 # Instructions append
 
+## Implementation
+
 You also need to implement a `equal/2` function. For this you can consider
 two numbers as equal, when the difference of each component is less than 0.005.

exercises/practice/hamming/.docs/instructions.append.md

@@ -1 +1,5 @@
+# Instructions append
+
+## Implementation
+
 If the sequences are not of equal length, return a tuple of `{error, badarg}`. Otherwise, return only the integer.

exercises/practice/robot-simulator/.docs/instructions.append.md

@@ -1,5 +1,7 @@
 # Instructions append
 
+## Implementation
+
 This exercise does require some kind of global state for your
 robot. In erlang this can be done in various ways (starting with most
 idiomatic one):