tlshd: Translate kernel-style Doxygen comments in src/tlshd/main.c

I started the ktls-utils project using the Linux kernel flavor of
Doxygen commenting which user-space Doxygen does not recognize by
default.

Convert existing comments in main.c to what a normal user space
Doxygen run expects to see. This will enable deployment of an
automatically-generated documentation web site.

Signed-off-by: Chuck Lever <[email protected]>

Author: chucklever

src/tlshd/main.c

@@ -1,9 +1,13 @@
-/*
- * Handle a request for a TLS handshake on behalf of an
- * in-kernel TLS consumer.
+/**
+ * @file main.c
+ * @brief Handle a request for a TLS handshake on behalf of an
+ *	  in-kernel TLS consumer
  *
+ * @copyright
  * Copyright (c) 2022 - 2023 Oracle and/or its affiliates.
- *
+ */
+
+/*
  * ktls-utils is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
  * published by the Free Software Foundation; version 2.
@@ -56,11 +60,23 @@ static const struct option longopts[] = {
 	{ NULL,		0,			NULL,	 0 }
 };
 
-static void usage(const char *progname)
+/**
+ * @brief Emit a program usage message on stderr
+ * @param[in]     progname  NUL-terminated C string containing program name
+ */
+static void usage(char *progname)
 {
 	fprintf(stderr, "usage: %s [-chsv]\n", progname);
 }
 
+/**
+ * @brief tlshd program entry point
+ * @param[in]     argc  Count of elements in "argv"
+ * @param[in]     argv  Command line parameters
+ *
+ * @retval EXIT_SUCCESS  Program terminated normally
+ * @retval EXIT_FAILURE  Program encountered an error
+ */
 int main(int argc, char **argv)
 {
 	static gchar config_file[PATH_MAX + 1];