add example and readme

example.c

@@ -0,0 +1,28 @@
+// Build with: gcc example.c c2html.c -o example -Wall -Wextra
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include "c2html.h"
+
+int main()
+{
+    // Table mode refers to the structure of the output HTML.
+    // If table_mode is turned off, then the output lines are
+    // separated by <br /> tags and there are no line numbers.
+    // Using table mode, then the lines are represented as rows
+    // of an HTML. The table has a first column with the line
+    // numbers and the second with their content.
+    _Bool table_mode = 0;
+    const char *prefix = NULL;
+
+    char *c = 
+      "int main() {\n"
+      "  int a = 5;\n"
+      "  return 0;\n"
+      "}\n";
+
+    char *html = c2html(c, strlen(c), table_mode, prefix, NULL);
+    printf("%s\n", html);
+    free(html);
+    return 0;
+}