add command-line arguments

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diff --git a/libs/cargs/docs/index.md b/libs/cargs/docs/index.md
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+---
+title: C/C++ Command Line Argument Parser
+description: cargs is a lightweight C/C++ command line argument parser library which can be used to parse argv and argc parameters passed to a main function.
+---
+
+## What is cargs? 
+**cargs** is a lightweight C/C++ command line argument parser library which can be used to parse argv and argc parameters passed to a main function.
+
+## Example
+Here is a simple example of cargs in action.
+ ```c
+#include <cargs.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+/**
+ * This is the main configuration of all options available.
+ */
+static struct cag_option options[] = {
+  {.identifier = 's',
+   .access_letters = "s",
+   .access_name = NULL,
+   .value_name = NULL,
+   .description = "Simple flag"},
+
+  {.identifier = 'm',
+    .access_letters = "mMoO",
+    .access_name = NULL,
+    .value_name = NULL,
+    .description = "Multiple access letters"},
+
+  {.identifier = 'l',
+    .access_letters = NULL,
+    .access_name = "long",
+    .value_name = NULL,
+    .description = "Long parameter name"},
+
+  {.identifier = 'k',
+    .access_letters = "k",
+    .access_name = "key",
+    .value_name = "VALUE",
+    .description = "Parameter value"},
+
+  {.identifier = 'h',
+    .access_letters = "h",
+    .access_name = "help",
+    .description = "Shows the command help"}};
+
+/**
+ * This is a custom project configuration structure where you can store the
+ * parsed information.
+ */
+struct demo_configuration
+{
+  bool simple_flag;
+  bool multiple_flag;
+  bool long_flag;
+  const char *key;
+};
+
+int main(int argc, char *argv[])
+{
+  char identifier;
+  const char *value;
+  cag_option_context context;
+  struct demo_configuration config = {false, false, false, NULL};
+
+  /**
+   * Now we just prepare the context and iterate over all options. Simple!
+   */
+  cag_option_prepare(&context, options, CAG_ARRAY_SIZE(options), argc, argv);
+  while (cag_option_fetch(&context)) {
+    identifier = cag_option_get(&context);
+    switch (identifier) {
+    case 's':
+      config.simple_flag = true;
+      break;
+    case 'm':
+      config.multiple_flag = true;
+      break;
+    case 'l':
+      config.long_flag = true;
+      break;
+    case 'k':
+      value = cag_option_get_value(&context);
+      config.key = value;
+      break;
+    case 'h':
+      printf("Usage: cargsdemo [OPTION]...\n");
+      printf("Demonstrates the cargs library.\n\n");
+      cag_option_print(options, CAG_ARRAY_SIZE(options), stdout);
+      printf("\nNote that all formatting is done by cargs.\n");
+      return EXIT_SUCCESS;
+    }
+  }
+
+  printf("simple_flag: %i, multiple_flag: %i, long_flag: %i, key: %s\n",
+    config.simple_flag, config.multiple_flag, config.long_flag,
+    config.key ? config.key : "-");
+
+  return EXIT_SUCCESS;
+}
+
+```
+
+### Example output
+```console
+foo@bar:~$ ./cargsdemo 
+simple_flag: 0, multiple_flag: 0, long_flag: 0, key: -
+```  
+<br>
+```console
+foo@bar:~$ ./cargsdemo -k=test -sm --long
+simple_flag: 1, multiple_flag: 1, long_flag: 1, key: test
+```  
+<br>
+```console
+foo@bar:~$ ./cargsdemo --help
+Usage: cargsdemo [OPTION]...
+Demonstrates the cargs library.
+
+  -s                   Simple flag
+  -m, -M, -o, -O       Multiple access letters
+  --long               Long parameter name
+  -k, --key=VALUE      Parameter value
+  -h, --help           Shows the command help
+
+Note that all formatting is done by cargs.
+```