Docs: caught up with v0.13.0 to v0.19.0

The documentation had kept up feature page by feature page and nowhere
else. Now also:

- the home page's App cards (notes of any size, pictures, sharing) and its
  note (the Shell, the VPN, the screenshot key);
- the guide: VPN in the Status Bar and in Settings, the three keys that work
  everywhere, screenshots of the Shell, a picture, sharing, the VPN page and
  the help panel;
- three how-tos: move files with your phone, set up the VPN, take a
  screenshot; where the files are and what things cost in memory;
- the FAQ: screenshots, and what listens on the network;
- the README's opening: what the firmware does today;
- the glossary: Tunnel, Sharing, Screenshot;
- every milestone's status line, with the version each thing shipped in.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

site/data/apps.toml

@@ -45,7 +45,7 @@ icon = 3
 num = "06"
 tag = "Notes"
 title = "Write it down"
-text = "Keep plain text notes on the SD card. There is no save key: the editor writes five seconds after you stop typing, through a temporary file, so a power cut never costs the note."
+text = "Keep plain text notes on the SD card, of any size: a megabyte opens as fast as a line. There is no save key: the editor writes five seconds after you stop typing, so a power cut never costs the note."
 fact = "Plain .txt files in /notes"
 icon = 6
 
@@ -53,7 +53,7 @@ icon = 6
 num = "07"
 tag = "Storage"
 title = "Manage the SD card"
-text = "Browse, copy, cut, rename and delete with a clipboard. Copies run in the background and Back cancels one. Opens text, hex, captures, tracks and update files."
+text = "Browse, copy, cut, rename and delete with a clipboard. Opens text, pictures, hex, captures, tracks and update files. Press w and the card is a web page in your phone's browser: upload and download with nothing to install."
 fact = "Checks every copy by size"
 icon = 8