add instructions for installing curl in the container

improving visibility of user inputs

Author: Xronophobe

chapter_09_docker.asciidoc

@@ -1019,7 +1019,7 @@ so that you can be sure of what's being run inside vs outside containers.
 [subs="specialcharacters,macros"]
 ----
 $ pass:quotes[*docker exec -it container-id-or-name bash*]
-root@5ed84681fdf8:/src# pass:specialcharacters,quotes[*apt-get update && apt-get install -y curl*]
+root@5ed84681fdf8:/src# pass:specialcharacters,quotes[*apt-get update && apt-get install -y curl*]  #<1>
 Get:1 pass:[http://deb.debian.org/debian] bookworm InRelease [151 kB]
 Get:2 pass:[http://deb.debian.org/debian] bookworm-updates InRelease [52.1 kB]
 [...]
@@ -1029,7 +1029,7 @@ Reading state information... Done
 The following additional packages will be installed:
   libbrotli1 libcurl4 libldap-2.5-0 libldap-common libnghttp2-14 libpsl5
 [...]
-root@5ed84681fdf8:/src# pass:quotes[*curl -iv http://localhost:8888*]
+root@5ed84681fdf8:/src# pass:quotes[*curl -iv http://localhost:8888*]  #<2>
 *   Trying 127.0.0.1:8888...
 * Connected to localhost (127.0.0.1) port 8888 (#0)
 > GET / HTTP/1.1
@@ -1057,6 +1057,15 @@ HTTP/1.1 200 OK
 </html>
 ----
 
+// CSANAD: I think the readers' inputs were a little difficult to spot, so I added some in-
+//         structions (and they kept causing a "no callout found for..." error, so I'll just leave
+// them here as comments:
+// <1> First we have to install `curl` as it isn't available in the `slim` images by default.
+//
+// <2> Then, we check whether we are able to request the site.
+
+
+
 That's definitely some HTML! And the `<title>To-Do lists</title>` looks like it's our html, too.
 
 So, we can see Django is serving our site _inside_ the container,