Consider providing a default key binding to toggle eldoc

[stormwatch]

I found out that I am almost always in need of toggling on and off (but mostly off) eldoc, so I added the following to eldoc's use package configuration

+  :init
+  (+map! "te" #'eldoc-mode)

I'm always hesitant about proposing things that add up in detriment of minimalism but it seemed useful for me in this particular case.