[skip-changelog] Removed direct links to gnu.org because the site is often down (#2821)

and it makes the linkcheck job to fail.

Author: cmaglie

README.md

@@ -43,7 +43,7 @@ e-mail contact: [email protected]
 
 ## License
 
-Arduino CLI is licensed under the [GPL 3.0] license.
+Arduino CLI is licensed under the GPL-3.0 license.
 
 You can be released from the requirements of the above license by purchasing a commercial license. Buying such a license
 is mandatory if you want to modify or otherwise use the software for commercial activities involving the Arduino
@@ -59,4 +59,3 @@ [email protected]
 [contributors]: https://github.com/arduino/arduino-cli/graphs/contributors
 [nightly builds]: https://arduino.github.io/arduino-cli/latest/installation/#nightly-builds
 [security policy]: https://github.com/arduino/arduino-cli/security/policy
-[gpl 3.0]: https://www.gnu.org/licenses/gpl-3.0.en.html

docs/FAQ.md

@@ -27,8 +27,8 @@ Additional board options have to be separated by commas (instead of colon):
 The serial monitor is available through the [monitor command][monitor command]. By the way, the functionality provided
 by this command is very limited and you may want to look for other tools if you need more advanced functionality.
 
-There are many excellent serial terminals to chose from. On Linux or macOS, you may already have [screen][screen]
-installed. On Windows, a good choice for command line usage is Plink, included with [PuTTY][putty].
+There are many excellent serial terminals to chose from. On Linux or macOS, you may already have `screen` installed. On
+Windows, a good choice for command line usage is Plink, included with [PuTTY][putty].
 
 ## How to change monitor configuration?
 
@@ -60,7 +60,6 @@ If your question wasn't answered, feel free to ask on [Arduino CLI's forum board
 [arduino cli board list]: commands/arduino-cli_board_list.md
 [0]: platform-specification.md
 [1]: https://forum.arduino.cc/c/software/arduino-cli/89
-[screen]: https://www.gnu.org/software/screen/manual/screen.html
 [putty]: https://www.chiark.greenend.org.uk/~sgtatham/putty/
 [monitor command]: commands/arduino-cli_monitor.md
 [configuration parameters]: pluggable-monitor-specification.md#describe-command