feat: add write_datasources an fix pkgdown #36

Job	Run time
Check NN version / macos-latest (R 4.3.1, 2023-10-25)	1m 56s
Check current version / macos-latest (release)	2m 30s
Coverage report / test-coverage-internal	1m 38s
Check NN version / macos-latest (R 4.4.1, 2024-08-06)	2m 15s
Check current version / windows-latest (release)	3m 44s
Check NN version / windows-latest (R 4.3.1, 2023-10-25)	6m 3s
Check current version / ubuntu-latest (devel)	2m 17s
Check NN version / windows-latest (R 4.4.1, 2024-08-06)	3m 44s
Check current version / ubuntu-latest (release)	2m 43s
Check NN version / ubuntu-latest (R 4.3.1, 2023-10-25)	24m 58s
Check current version / ubuntu-latest (oldrel-1)	2m 39s
Check NN version / ubuntu-latest (R 4.4.1, 2024-08-06)	25m 0s
Pkgdown site / pkgdown	2m 5s
Megalinter / MegaLinter	2m 50s
	1h 24m 22s

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