Added description of how to set custom feedback for incorrect responses to docs

Author: KarlLundengaard

app/docs/user.md

@@ -1,3 +1,10 @@
 # ArrayEqual
 
-This function is used to compare two number arrays/vectors/matrices, provided absolute and/or relative tolerance parameters `rtol` and `atol`. This is carried out using the [numpy.allclose](https://numpy.org/doc/stable/reference/generated/numpy.allclose.html) function.
+This function is used to compare two number arrays/vectors/matrices, provided absolute and/or relative tolerance parameters `rtol` and `atol`. This is carried out using the [numpy.allclose](https://numpy.org/doc/stable/reference/generated/numpy.allclose.html) function.
+
+### Optional parameters
+
+There is one optional parameter: `feedback_for_incorrect_case`.
+
+## `feedback_for_incorrect_case`
+All feedback for all incorrect responses will be replaced with the string that this parameter is set to.