Remove unsupported formats from Diff command help text #629

Job	Run time
Elixir 1.13.4 OTP 24.3 - Credo running on Elixir v1.13 source code	58s
Elixir 1.14.5 OTP 24.3 - Credo running on Elixir v1.13 source code	55s
Elixir 1.13.4 OTP 25.3 - Credo running on Elixir v1.13 source code	55s
Elixir 1.15.7 OTP 25.3 - Credo running on Elixir v1.13 source code	54s
Elixir 1.16.2 OTP 25.3 - Credo running on Elixir v1.13 source code	53s
Elixir 1.17.3 OTP 25.3 - Credo running on Elixir v1.13 source code	52s
Elixir 1.15.7 OTP 26.2 - Credo running on Elixir v1.13 source code	59s
Elixir 1.16.2 OTP 26.2 - Credo running on Elixir v1.13 source code	55s
Elixir 1.17.3 OTP 26.2 - Credo running on Elixir v1.13 source code	54s
Elixir 1.13.4 OTP 24.3 - Credo running on Elixir main source code	58s
Elixir 1.14.5 OTP 24.3 - Credo running on Elixir main source code	1m 1s
Elixir 1.13.4 OTP 25.3 - Credo running on Elixir main source code	1m 0s
Elixir 1.15.7 OTP 25.3 - Credo running on Elixir main source code	58s
Elixir 1.16.2 OTP 25.3 - Credo running on Elixir main source code	59s
Elixir 1.17.3 OTP 25.3 - Credo running on Elixir main source code	1m 1s
Elixir 1.15.7 OTP 26.2 - Credo running on Elixir main source code	1m 0s
Elixir 1.16.2 OTP 26.2 - Credo running on Elixir main source code	58s
Elixir 1.17.3 OTP 26.2 - Credo running on Elixir main source code	57s
	17m 7s

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