env: Add a command to display details about env flags

Similar to the env callback command, this will show details about the
options available, the static list, and the currently active variables.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/README b/README
index acb711a..08c0fcc 100644
--- a/README
+++ b/README
@@ -816,6 +816,7 @@
 		CONFIG_CMD_EEPROM	* EEPROM read/write support
 		CONFIG_CMD_ELF		* bootelf, bootvx
 		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
+		CONFIG_CMD_ENV_FLAGS	* display details about env flags
 		CONFIG_CMD_EXPORTENV	* export the environment
 		CONFIG_CMD_EXT2		* ext2 command support
 		CONFIG_CMD_EXT4		* ext4 command support