apply suggestions about UPGRADING.md

Author: umbynos

docs/UPGRADING.md

@@ -6,13 +6,13 @@ Here you can find a list of migration guides to handle breaking changes between
 
 ### `board details` arguments change
 
-The `board details` command now accepts only the `-b` flag to specify the FQBN.
+The `board details` command now accepts only the `--fqbn` or `-b` flags to specify the FQBN.
 
 The previously deprecated `board details <FQBN>` syntax is no longer supported.
 
 ### `board attach` arguments change
 
-The `board attach` command now uses `-p` and `-b` flags to respectively select the board FQBN and the port.
+The `board attach` command now uses `--port` and `-p` flags to set board port and `--board` and `-b` flags to select its FQBN.
 
 The previous syntax `board attach <port>|<FQBN> [sketchPath]` is no longer supported.