Revise sign (#6581)

* update docs

* add sign to intActivationTypes

* add RTTI macro

* update backend test

* add type prp test

* add visitor test

* add visitor and type_prop test to CMakeList

* add sign to constants.py

* delete backend tests and create new reference tests

* style fix

* remoove sign backend test from CMakeList

* create reference test for all supported types

* remove boolean type from evaluate method

docs/ops/arithmetic/Sign_1.md

@@ -4,33 +4,30 @@
 
 **Category**: Arithmetic unary operation
 
-**Short description**: *Sign* performs element-wise sign operation with given tensor.
+**Short description**: *Sign* performs element-wise sign operation on a given input tensor.
 
-**Attributes**:
-
-    No attributes available.
-
-**Inputs**
-
-* **1**: An tensor of type *T*. **Required.**
-
-**Outputs**
-
-* **1**: The result of element-wise sign operation. A tensor of type *T* with mapped elements of the input tensor to -1 (if it is negative), 0 (if it is zero), or 1 (if it is positive).
-
-**Types**
-
-* *T*: any numeric type.
-
-*Sign* does the following with the input tensor *a*:
+**Detailed description**: *Sign* performs element-wise sign operation on a given input tensor, based on the following mathematical formula:
 
 \f[
 a_{i} = sign(a_{i})
 \f]
 
-**Examples**
+**Attributes**: *Sign* operation has no attributes.
 
-*Example 1*
+**Inputs**
+
+* **1**: A tensor of type *T* and arbitrary shape. **Required.**
+
+**Outputs**
+
+* **1**: The result of element-wise *Sign* operation. A tensor of type *T* with mapped elements of the input tensor to -1 (if it is negative), 0 (if it is zero), or 1 (if it is positive).
+
+**Types**
+
+* *T*: any numeric type.
+
+
+**Example**
 
 ```xml
 <layer ... type="Sign">