docs: Add fake LDAP auth to subsystems/auth.md.
docs: Add fake LDAP auth to subsystems/auth.md.

Fixes #10297.

punchagan/zulip,synicalsyntax/zulip,punchagan/zulip,rht/zulip,zulip/zulip,jackrzhang/zulip,kou/zulip,kou/zulip,zulip/zulip,synicalsyntax/zulip,shubhamdhama/zulip,dhcrzf/zulip,kou/zulip,andersk/zulip,jackrzhang/zulip,eeshangarg/zulip,brainwane/zulip,andersk/zulip,dhcrzf/zulip,eeshangarg/zulip,rht/zulip,zulip/zulip,shubhamdhama/zulip,hackerkid/zulip,jackrzhang/zulip,showell/zulip,tommyip/zulip,rishig/zulip,kou/zulip,tommyip/zulip,brainwane/zulip,eeshangarg/zulip,zulip/zulip,timabbott/zulip,synicalsyntax/zulip,rht/zulip,andersk/zulip,hackerkid/zulip,kou/zulip,punchagan/zulip,tommyip/zulip,shubhamdhama/zulip,brainwane/zulip,jackrzhang/zulip,rishig/zulip,kou/zulip,brainwane/zulip,brainwane/zulip,zulip/zulip,rishig/zulip,timabbott/zulip,punchagan/zulip,andersk/zulip,dhcrzf/zulip,rishig/zulip,hackerkid/zulip,shubhamdhama/zulip,tommyip/zulip,jackrzhang/zulip,hackerkid/zulip,showell/zulip,jackrzhang/zulip,timabbott/zulip,eeshangarg/zulip,synicalsyntax/zulip,showell/zulip,dhcrzf/zulip,synicalsyntax/zulip,timabbott/zulip,zulip/zulip,kou/zulip,dhcrzf/zulip,shubhamdhama/zulip,rht/zulip,andersk/zulip,showell/zulip,tommyip/zulip,eeshangarg/zulip,rht/zulip,tommyip/zulip,hackerkid/zulip,hackerkid/zulip,zulip/zulip,shubhamdhama/zulip,brainwane/zulip,synicalsyntax/zulip,timabbott/zulip,punchagan/zulip,jackrzhang/zulip,punchagan/zulip,timabbott/zulip,hackerkid/zulip,rishig/zulip,synicalsyntax/zulip,andersk/zulip,rishig/zulip,showell/zulip,tommyip/zulip,rht/zulip,brainwane/zulip,dhcrzf/zulip,punchagan/zulip,eeshangarg/zulip,showell/zulip,shubhamdhama/zulip,eeshangarg/zulip,andersk/zulip,dhcrzf/zulip,rht/zulip,rishig/zulip,showell/zulip,timabbott/zulip