This <https://orgmode.org/manual/Setting-tags.html#Setting-tags> describes
a org-tag-alist for setting up globally a list of tags, but I'm not sure
how to alter org-tag-alist. I'm used to doing an M-x customize-variable,
but there is no org-tag-alist. Later on the page it has this form:

(setq org-tag-alist '(("@work" . ?w) ("@home" . ?h) ("laptop" . ?l)))

which seems to be something to put in my .emacs, i.e., org-tag-alist is not
an existing variable?

LB