Man pages matching name pmdainit in section 3:

pmdaInit.3.en	debian 10 / libpcp-pmda3-dev
pmdainit.3.en	debian 10 / libpcp-pmda3-dev
pmdaInit.3.en	debian 11 / libpcp-pmda3-dev
pmdaInit.3.en	debian 12 / libpcp-pmda3-dev