footnotes markdown extension fails validation #3919
Description
In https://github.com/juntyr/numcodecs-rs, I use footnotes for one of the Python packages. Building MkDocs in strict mode gives the following messages:
INFO - Doc file 'api/numcodecs_wasm_random_projection/index.md' contains a link '#numcodecs_wasm_random_projection.RandomProjection--fn:1', but there is no
such anchor on this page.
INFO - Doc file 'api/numcodecs_wasm_random_projection/index.md' contains a link '#numcodecs_wasm_random_projection.RandomProjection--fn:2', but there is no
such anchor on this page.
INFO - Doc file 'api/numcodecs_wasm_random_projection/index.md' contains a link '#numcodecs_wasm_random_projection.RandomProjection--fnref:1', but there is no
such anchor on this page.
INFO - Doc file 'api/numcodecs_wasm_random_projection/index.md' contains a link '#numcodecs_wasm_random_projection.RandomProjection--fnref:2', but there is no
such anchor on this page.
These links are the forward and backward links of the footnotes.