harmonize Info and docstrings

[jidanni@xxxxxxxxxxx]

I wish there was a key like T (w3m-toggle-inline-images) that only
affected the current page, and only once.

Wait, In Info I see
  `t' (Lynx-like keymap)
  `i' (Info-like keymap)
     Toggle displaying of the single inline image
     under the cursor (`w3m-toggle-inline-image').
                      ^or the region. <-- please add this that I found
mentioned in the docstring, or else I would have never known that it
does just about what I want: I can now do C-x h (mark-whole-buffer)
then t (w3m-toggle-inline-image).

Indeed, all the Info items need to mention such important points from
the docstrings.