Tweak `markdownlint` rules and README versioning (#286) #774

Job	Run time
Environment variables (25, v1.14, 1.0.0, nightly, ubuntu-latest)	13s
OTP 27, Elixir v1.17.0, Gleam , rebar3 3.23	21s
OTP 26.0, Elixir v1.14-otp-25, Gleam , rebar3	16s
OTP 26.0, Elixir 1.14.5, Gleam , rebar3	14s
OTP 25.2, Elixir 1.14.2, Gleam , rebar3	12s
OTP 25.2, Elixir 1.14.3, Gleam , rebar3	13s
OTP 27, Elixir , Gleam , rebar3	8s
OTP 26, Elixir , Gleam , rebar3	6s
OTP 25, Elixir , Gleam , rebar3	7s
OTP 25, Elixir 1.16, Gleam , rebar3 3	18s
OTP 24, Elixir 1.16, Gleam , rebar3 3	19s
OTP 25.0, Elixir v1.13.4-otp-25, Gleam , rebar3 3.18.0	17s
OTP 25.0, Elixir v1.13.4, Gleam , rebar3 3.18.0	18s
OTP 25, Elixir , Gleam , rebar3 nightly	12s
OTP 26, Elixir , Gleam , rebar3 nightly	12s
OTP 20, Elixir v1.4, Gleam , rebar3 3.15.0	18s
OTP 20, Elixir v1.4, Gleam , rebar3 3.11	20s
OTP 21, Elixir v1.6, Gleam , rebar3 3.12	21s
OTP 22, Elixir v1.7, Gleam , rebar3 3.13	22s
OTP 23, Elixir v1.10, Gleam , rebar3 3.14	16s
OTP 25.0.2, Elixir v1.13.4, Gleam , rebar3 3.19	25s
OTP 24, Elixir v1.12, Gleam , rebar3 3.15	19s
OTP 22.3.4.2, Elixir v1.11.0, Gleam , rebar3	12s
OTP 22.3.4.1, Elixir 1.10.3, Gleam , rebar3	10s
OTP 23.1, Elixir main, Gleam , rebar3	10s
OTP 25, Elixir main, Gleam , rebar3	13s
OTP 24, Elixir , Gleam 0.23, rebar3	12s
OTP 24, Elixir , Gleam 0.23.0-rc1, rebar3	12s
OTP false, Elixir , Gleam 0.23.0-rc1, rebar3	8s
OTP 24, Elixir , Gleam 0.22.0, rebar3	13s
OTP 24, Elixir v1.13, Gleam , rebar3	17s
	7m 34s

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