Internally at Meta we have over a hundred websites that use docusaurus for internal documentation. Currently these do not have a way to display last modified date since we use mercurial internally. Currently docusaurus supports only git VCS to extract last modified date for each file. I propose to add support for alternative last modified date sources. I am not sure whether making hg a first class citizen in docusaurus is the right solution. Perhaps exposing an API to overwrite can be an alternative solution. We have a common preset for the internal sites where we could use such API to support our internal mercurial version.