posix: c_lib_ext: fnmatch: added Doxygen

Added Doxygen on new functions and on fnmatch function

Signed-off-by: Harun Spago <harun.spago.code@gmail.com>

Author: Spago123

include/zephyr/posix/fnmatch.h

@@ -36,21 +36,34 @@
 #ifndef _FNMATCH_H_
 #define _FNMATCH_H_
 
-#define FNM_NOMATCH 1 /* Match failed. */
+#define FNM_NOMATCH 1 /**< Match failed */
 #define FNM_NOSYS   2 /* Function not implemented. */
 #define FNM_NORES   3 /* Out of resources */
 
-#define FNM_NOESCAPE	0x01 /* Disable backslash escaping. */
-#define FNM_PATHNAME	0x02 /* Slash must be matched by slash. */
-#define FNM_PERIOD	0x04 /* Period must be matched by period. */
-#define FNM_CASEFOLD	0x08 /* Pattern is matched case-insensitive */
-#define FNM_LEADING_DIR 0x10 /* Ignore /<tail> after Imatch. */
+#define FNM_NOESCAPE    0x01 /**< Disable backslash escaping */
+#define FNM_PATHNAME    0x02 /**< Slash must be matched by slash */
+#define FNM_PERIOD      0x04 /**< Period must be matched by period */
+#define FNM_CASEFOLD    0x08 /**< Pattern is matched case-insensitive */
+#define FNM_LEADING_DIR 0x10 /**< Only match the initial segment of a string up to the first '/' */
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-int fnmatch(const char *, const char *, int);
+/**
+ * @brief Check if a filename or input string matches a shell-style matching pattern.
+ *
+ * @param pattern pattern that is matched against @param string
+ * @param string input string to match against @param pattern
+ * @param flags flags used to signal special matching conditions such as @ref FNM_NOESCAPE
+ * 
+ * 
+ * @retval 0 pattern found in string
+ * @retval FNM_NOMATCH pattern not found in string
+ * @retval FNM_NORES recursion limit reached
+ * @retval FNM_NOSYS function not implemented
+ */
+int fnmatch(const char *pattern, const char *string, int flags);
 
 #ifdef __cplusplus
 }