Added parameters documentation

Author: paulorb

docs/getting-started/input-parameters.md

@@ -0,0 +1,37 @@
+# Input parameters
+
+Simulator supports input parameters, these parameters are defined on the xml file with optional default values which can be customized by command line arguments.
+
+## How to configure the parameters?
+
+1. Adding parameters section to the XML
+2. Define the parameters and its optional default value (in case the default value is not specified this parameter becomes mandatory)
+
+```xml
+<?xml version="1.0" encoding="US-ASCII" ?>
+<device ip="0.0.0.0" port="502">
+    <parameters>
+        <parameter symbol="PARAM_CURRENT_SELECTION" datatype="INT16">15</parameter>
+        <parameter symbol="PARAM_SET_TEMPERATURE" datatype="FLOAT32">5.45</parameter>
+        <parameter symbol="PARAM_ENABLE_FAST_MODE" datatype="BOOL">1</parameter>
+    </parameters>
+    <configuration initializeUndefinedRegisters="true" initialValue="0">
+        ...
+    </configuration>
+    <simulation plcScanTime="1000">
+        ...
+    </simulation>
+</device>
+```
+
+These parameters can be used like any other register on the simulation, but as **read-only variables**.
+
+## How to change the parameters dynamically?
+Specified parameters can be overwritten by command line arguments, by specifying the argument -e -env.
+
+Example:
+```
+docker run -it -v $PWD/:/simulation -p5002:5002 paulorb/modbus-simulator-cli   -f /simulation/configuration-simulation.xml -e PARAM_CURRENT_SELECTION=10 -e PARAM_SET_TEMPERATURE=0.5
+```
+
+Please note the value specified as argument needs to match the parameter's datatype specified on the xml.

mkdocs.yml

@@ -18,6 +18,7 @@ nav:
       - Overview: index.md
       - Quick start: getting-started/quick-start.md
       - Operations: getting-started/operations.md
+      - Input parameters: getting-started/input-parameters.md
       - License: getting-started/license.md
       - Contributing: getting-started/contributing.md