docs: name the stop keys a computer has

First install said B or Ctrl+C stops the run, where a computer's screen
says Esc or Ctrl-C and the b key does nothing.

tests/test_doc_pages.py

@@ -682,6 +682,16 @@ class FirstInstallWalkthrough(unittest.TestCase):
         self.text = _page("first-install.md")
         self.run = _page("installer.md")
 
+    def test_the_stop_keys_are_the_ones_the_screen_names(self):
+        """The page said "B or Ctrl+C stops it" for a computer, whose screen
+        says Esc or Ctrl-C, and where the b key does nothing."""
+        import install
+
+        section = _section(self.text, "4. Wait")
+        computer = install._STOP_KEYS["keys"][0].replace("Ctrl-C", "Ctrl+C")
+        self.assertIn(f"{computer} stops", section)
+        self.assertIn(f"{install._STOP_KEYS['gptokeyb'][0]} on a handheld", section)
+
     def test_no_hand_kept_size_before_the_run(self):
         import install
 

wiki/first-install.md

@@ -87,7 +87,7 @@ Arrows move, Enter chooses, Esc goes back. A handheld's A and B do the same.
 
 ## 3. Install
 
-The next screen counts the missing files and the free space.
+The next screen counts missing files and free space.
 Press Enter on **Install**. **Choose systems** keeps the consoles you
 play.
 
@@ -96,7 +96,7 @@ card or a folder**, then the card. It stays unchanged.
 
 ## 4. Wait
 
-B or Ctrl+C stops it. Run it again to carry on.
+Esc or Ctrl+C stops, B on a handheld. Run again to resume.
 
 ## 5. Read the result