Add documentation for production settings configuration and usage

Author: grongierisc

docs/img/custom_settings.png

@@ -0,0 +1,102 @@
+# Settings in production
+
+To pass production settings to your component, you have two options:
+
+- Use the **%settings** parameter
+- Create your custom settings
+
+## Context
+
+In production when you select a component, you can configure it by passing settings.
+
+![Settings in production](img/settings-in-production.png)
+
+Those settings can be passed to your python code.
+
+## Use the %settings parameter
+
+All the settings passed to **%settings** are available in string format into your class as a root attribute.
+
+Each line of the **%settings** parameter is a key-value pair separated by a the equal sign.
+
+Key will be the name of the attribute and value will be the value of the attribute.
+
+For example, if you have the following settings:
+
+```text
+foo=bar
+my_number=42
+```
+
+You can access those settings in your class like this:
+
+```python
+from iop import BusinessOperation
+
+class MyBusinessOperation(BusinessOperation):
+    
+    def on_init(self):
+        self.log_info("[Python] MyBusinessOperation:on_init() is called")
+        self.log_info("[Python] foo: " + self.foo)
+        self.log_info("[Python] my_number: " + self.my_number)
+        return
+```
+
+As **%settings** is a free text field, you can pass any settings you want.
+
+Meaning you should verify if the attribute exists before using it.
+
+```python
+from iop import BusinessOperation
+
+class MyBusinessOperation(BusinessOperation):
+    
+    def on_init(self):
+        self.log_info("[Python] MyBusinessOperation:on_init() is called")
+        if hasattr(self, 'foo'):
+            self.log_info("[Python] foo: " + self.foo)
+        if hasattr(self, 'my_number'):
+            self.log_info("[Python] my_number: " + self.my_number)
+        return
+```
+
+## Create your custom settings
+
+If you want to have a more structured way to pass settings, you can create your custom settings.
+
+To create a custom settings, you create an attribute in your class.
+
+This attribute must :
+
+- have an default value. 
+- don't start with an underscore.
+- be untyped or have the following types: `str`, `int`, `float`, `bool`.
+
+Otherwise, it will not be available in the managment portal.
+
+```python
+from iop import BusinessOperation
+
+class MyBusinessOperation(BusinessOperation):
+
+    # This setting will be available in the managment portal
+    foo: str = "default"
+    my_number: int = 42
+    untyped_setting = None
+
+    # This setting will not be available in the managment portal
+    _my_internal_setting: str = "default"
+    no_aviable_setting
+    
+    def on_init(self):
+        self.log_info("[Python] MyBusinessOperation:on_init() is called")
+        self.log_info("[Python] foo: " + self.foo)
+        self.log_info("[Python] my_number: " + str(self.my_number))
+        return
+```
+
+They will be available in the managment portal as the following:
+
+![Custom settings](img/custom_settings.png)
+
+If you overwrite the default value in the managment portal, the new value will be passed to your class.

docs/img/settings-in-production.png

@@ -15,6 +15,7 @@ nav:
   - DTL Support: dtl.md
   - Logging: logging.md
   - Debugging: debug.md
+  - Production Settings: prod-settings.md
   - Reference:
     - Examples: example.md
     - Useful Links: useful-links.md