docs: the guide around four things and two screens, new screenshots, the plan closed

The guide opens with documents, cards, notes and diary entries, and the
documents and plan screens, then walks the day with the scratchpad, the
info sheet and cards linked both ways. The README and the wiki's home say
the same in short, and show the scratchpad and the info sheet. The
screenshot script drops its Alt keys and takes both. PLAN.md records the
simplification's slices, what was left of its navigation fixes, and the
backlog fitted to the model.

docs/wiki/Spaces-and-Documents.md

@@ -68,9 +68,13 @@ linked to from anywhere behind the login.
 The line under the title says when it was written and last edited, how many
 words it has, how many documents link to it, and whether it is public. Click it,
 or press `gi`, for the info sheet: the document's headings, its earlier
-versions, the documents that link to it and its share link, one part at a time
-— `Tab` goes to the next. `gO`, `gh` and `gb` open it at their own part. In the
-reader:
+versions, the documents that link to it, the cards about it, its files and its
+share link, one part at a time — `Tab` goes to the next. `gO`, `gh`, `gb` and
+`gc` open it at their own part.
+
+![The cards about a document, in its info sheet](../images/info.png)
+
+In the reader:
 
 | key | what it does |
 | --- | --- |