docs/Custom: minor rewording

Author: ukkopahis

docs/Basic_setup/Custom.md

@@ -2,25 +2,28 @@
 
 Each time you build the stack from the menu, the Docker Compose file
 `docker-compose.yml` is recreated, losing any custom changes you've made. There
-are three ways of dealing with this:
-
-1.  Not using the menu after you've made changes. Do remember to backup, in
-    case you overwrite it by mistake or habit from the menu.
-2.  Use the Docker Compose's [inbuilt override
-    mechanism](https://docs.docker.com/compose/extends/). This limits you to
-    changing values already present in your `docker-compose.yml`, but is handy
-    as changes are immediately picked by running `docker-compose up -d`.
+are different ways of dealing with this:
+
+1.  Not using the menu after you've made changes. Do remember to backup your
+    customized `docker-compose.yml`, in case you overwrite it by mistake or
+    habit from the menu.
+2.  Use the Docker Compose [inbuilt override mechanism](
+    https://docs.docker.com/compose/extends/) by creating a file named
+    `docker-compose.override.yml`. This limits you to changing values and
+    appending to lists already present in your docker-compose.yml, but it's
+    handy as changes are immediately picked up by docker-compose commands. To
+    see the resulting final config run `docker-compose config`.
 3.  IOTstack menu, in the default master-branch, implements a mechanism to
     merge the yaml file `compose-override.yml` with the menu-generated stack
     into `docker-compose.yml`. This can be used to add even complete new
     services. See below for details.
 4.  This is not an actual extension mechanism, but well worth mentioning: If
-    you need to add a new services that don't communicate with the services in
-    IOTstack, you can create it completely separately and independently into
-    its own folder, e.g. `~/customStack/docker-compose.yml`. These services can
-    then be independently managed by entering that folder: `cd ~/customStack`
-    and then using the `docker-compose` commands as normal. The best override is
-    the one you don't have to make.
+    you need a new services that doesn't communicate with the services in
+    IOTstack, create it completely separately and independently into its own
+    folder, e.g. `~/customStack/docker-compose.yml`. This composition can then
+    be independently managed from that folder: `cd ~/customStack` and use
+    `docker-compose` commands as normal. The best override is the one you don't
+    have to make.
 
 ## Custom services and overriding default settings for IOTstack
 You can specify modifcations to the `docker-compose.yml` file, including your own networks and custom containers/services.