Bug#39117 "plugin_load" option not documented

correct text describing the --plugin-load option to mysqld

sql/mysqld.cc:
  correct text describing the --plugin-load option to mysqld

sql/mysqld.cc

@@ -6666,9 +6666,10 @@ The minimum value for this variable is 4096.",
    "Directory for plugins.",
    (uchar**) &opt_plugin_dir_ptr, (uchar**) &opt_plugin_dir_ptr, 0,
    GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
-  {"plugin_load", OPT_PLUGIN_LOAD,
-   "Optional colon separated list of plugins to load, where each plugin is "
-   "identified by name and path to library seperated by an equals.",
+  {"plugin-load", OPT_PLUGIN_LOAD,
+   "Optional colon-separated list of plugins to load, where each plugin is "
+   "identified as name=library, where name is the plugin name and library "
+   "is the plugin library in plugin_dir.",
    (uchar**) &opt_plugin_load, (uchar**) &opt_plugin_load, 0,
    GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
   {"preload_buffer_size", OPT_PRELOAD_BUFFER_SIZE,