readme update

Author: jonas-merkle

README.md

@@ -2,10 +2,54 @@
 
 A collection of helper functions for the [Serilog.Extensions.Logging](https://www.nuget.org/packages/Serilog.Extensions.Logging) logging tool.
 
-
 ## Status
 
 |                       |                       |
 |----------------------:|-----------------------|
 | Nuget Package Version | [![Nuget Version](https://img.shields.io/nuget/v/jjm.one.Serilog.Extensions.Logging.Helpers?style=flat-square)](https://www.nuget.org/packages/jjm.one.Serilog.Extensions.Logging.Helpers/) |
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+
+## Table of contents
+
+- [jjm.one.Serilog.Extensions.Logging.Helpers](#jjmoneserilogextensionslogginghelpers)
+  - [Status](#status)
+  - [Table of contents](#table-of-contents)
+  - [Usage](#usage)
+    - [Use function logging](#use-function-logging)
+    - [Output of function logging](#output-of-function-logging)
+
+## Usage
+
+### Use function logging
+
+```csharp
+class MyClass {
+
+    // ...
+
+    void MyFancyFunction() {
+
+        // log the function call
+        Log.Logger.LogFctCall(GetType(), MethodBase.GetCurrentMethod(), LogEventLevel.Debug);
+
+        try {
+            
+            //...
+        }
+        catch (Exception exc) {
+
+            // Log the exception
+            Log.Logger.LogExcInFctCall(exc, GetType(), MethodBase.GetCurrentMethod(), "My custom exception message!", LogEventLevel.Error);
+        }
+    }
+
+    // ...
+}
+```
+
+### Output of function logging
+
+```text
+Function called: MyClass -> MyFancyFunction
+Exception thrown in: MyClass -> MyFancyFunction
+My custom exception message!
+```