docs(python): fix duplicated headings on layers and types API pages (… #6071

Job	Run time
s3 / 0_minio_s3 / fuzz_reader	5m 46s
fs / local_fs / fuzz_reader	5m 6s
azblob / azurite_azblob / fuzz_writer	6m 4s
fs / local_fs / fuzz_writer	5m 5s
memory / memory / fuzz_reader	5m 9s
azblob / azurite_azblob / fuzz_reader	6m 3s
memory / memory / fuzz_writer	5m 3s
s3 / 0_minio_s3 / fuzz_writer	5m 40s
	43m 56s

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