fix typo

docs/api/mg_callbacks.md

@@ -32,7 +32,7 @@
 |**`log_message`**|**`int (*log_message)( const struct mg_connection *conn, const char *message );`**|
 | |The callback function `log_message()` is called when CivetWeb is about to log a message. If the callback function returns 0, CivetWeb will use the default internal log routines to log the message. If a non-zero value is returned CivetWeb assumes that logging has already been done and no further action is performed.|
 |**`open_file`**|**`const char *(*open_file)( const struct mg_connection *conn, const char *path, size_t *data_len );`**|
-| |The callback function `open_file()` is called when a file is to be opened by CivetWeb. The callback can return a pointer to a memory location and set the memory block size in the variable pointed to by `data_len` to signal CivetWeb that the file should not be loaded from disk, but that instead a stored version in memory should be used. If the callback function returns NULL, CivetWeb will open the file from disk. This callback allows caching to be implementedi at the application side, or to serve specific files from static memory instead of from disk.|
+| |The callback function `open_file()` is called when a file is to be opened by CivetWeb. The callback can return a pointer to a memory location and set the memory block size in the variable pointed to by `data_len` to signal CivetWeb that the file should not be loaded from disk, but that instead a stored version in memory should be used. If the callback function returns NULL, CivetWeb will open the file from disk. This callback allows caching to be implemented at the application side, or to serve specific files from static memory instead of from disk.|
 |~~`upload`~~|**`void (*upload)( struct mg_connection * conn, const char *file_name );`**|
 | |*Deprecated. Use* `mg_handle_form_request()` *instead.* The callback function `upload()` is called when CivetWeb has uploaded a file to a temporary directory as result of a call to `mg_upload()`. The parameter `file_name` contains the full file name including path to the uploaded file.|
 |~~`websocket_connect`~~|**`int (*websocket_connect)( const struct mg_connection *conn );`**|