Editor indentation for Emacs and Sublime Text; container guides point to editor support (from dev 5d35f256476e)

doc/install/linux_container_install.md

@@ -111,6 +111,20 @@ The Standard Klammer Set is loaded by default. To load a different klammer set,
 pass `-k PATH` (the klammer set's `.k` file). To run with only the three
 primitive klammers (`@read`, `@eval`, `@cond`), use `-k none`.
 
+## Editor support (Emacs, Sublime Text)
+
+Editing Klammertext is nicer with editor support: syntax highlighting,
+delimiter matching, and indentation for Emacs and Sublime Text. It is not
+inside the container image — it belongs on your machine, next to your editor.
+Download it from either place:
+
+- <https://andykopra.com/Klammertext_editing.zip> — unpacks to `emacs/` and
+  `sublime/` folders
+- the Klammertext source repository,
+  <https://git.andykopra.com/ack/klammertext>, directory `doc/edit/`
+
+Each package's README explains its installation.
+
 ## If something goes wrong
 
 - **`Cannot connect to the Docker daemon`** — the Docker service isn't running: