Update flags constraints

Author: polldo

designs/0002-tags.md

@@ -39,10 +39,10 @@ These commands can be:
 `ota upload --device-tags <key0>=<value0>,<key1>=<value1> --file <sketch-file.ino.bin>` to perform an upload via ota to all the devices having all the tags passed
 
 
-To be decided, **which flag is mandatory and which is optional**:
+**flags constraints**:
 In delete and ota commands, the `--id` flag should become **optional** instead of mandatory. 
-Then, if neither `--id` nor `--tags` is passed, the command could return an error telling the user to specify at least one of the two flags.
-On the other hand, if both flags are passed, we could follow different approaches: return an error, use only one flag (only tags or only id), try to use both flags.
+Then, if neither `--id` nor `--tags` is passed, the command should return an error telling the user to specify at least one of the two flags.
+On the other hand, if both flags are passed, the command should return an error telling to choose only one of the two flags.
 
 Another thing to be decided is **how to handle errors**:
 - Try to execute the command on all the indicated resources, without stopping in case of errors. At the end, print all the errors details.