I have been asked to bring this document "Convention d’accueil" for short stay visa in France, with me on the date of appointment, I could not understand from where I can get this document? Any idea please?
It's a document you would get from a research institution if you are coming there for a few weeks to do research. It's not unusual for a professor or young researcher to go for a short time to another institution to exchange ideas, work on an empirical study or write a paper. If they stay for less than 90 days, they would not get a long-stay visa but this invitation and, if needed, a Schengen visa.
As I understand from your other questions, you won't be doing research at a French institution but merely attending a conference and you should not need that document. Do submit some invitation/proof of registration to the conference with your visa application.