docs: Remove customprofilefield from caveats in slack import doc.
docs: Remove customprofilefield from caveats in slack import doc.

This was added in #9035

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