Clean up "running NESTML" section in the docs

[clinssen]

Moves all platform-specific documentation to the platform-specific pages of the readme.

[github-actions]

Bencher Report

Branch	1254/merge
Testbed	ubuntu-latest

🚨 1 Alert

Iteration	Benchmark	Measure Units	View	Benchmark Result (Result Δ%)	Upper Boundary (Limit %)
0	tests/nest_continuous_benchmarking/test_nest_continuous_benchmarking.py::TestNESTContinuousBenchmarking::test_stdp_nn_synapse	Latency seconds (s)	📈 plot 🚷 threshold 🚨 alert (🔔)	3.78 s (+10.40%) Baseline: 3.42 s	3.77 s (100.36%)

Click to view all benchmark results

Benchmark	Latency	Benchmark Result seconds (s) (Result Δ%)	Upper Boundary seconds (s) (Limit %)
tests/nest_continuous_benchmarking/test_nest_continuous_benchmarking.py::TestNESTContinuousBenchmarking::test_stdp_nn_synapse	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	3.78 s (+10.40%) Baseline: 3.42 s	3.77 s (100.36%)

Benchmark	Latency	Benchmark Result seconds (s) (Result Δ%)	Upper Boundary seconds (s) (Limit %)
tests/nest_continuous_benchmarking/test_nest_continuous_benchmarking.py::TestNESTContinuousBenchmarking::test_stdp_nn_synapse	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	3.16 s (-7.33%) Baseline: 3.41 s	3.75 s (84.25%)

Benchmark	Latency	Benchmark Result seconds (s) (Result Δ%)	Upper Boundary seconds (s) (Limit %)
tests/nest_continuous_benchmarking/test_nest_continuous_benchmarking.py::TestNESTContinuousBenchmarking::test_stdp_nn_synapse	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	3.16 s (-7.39%) Baseline: 3.41 s	3.75 s (84.19%)

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