systemd, README: Edit for clarity

dist/init/linux-systemd/README.md

 # systemd unit for caddy
 
-Please do not hesitate to ask [me](mailto:klingt.net+caddy@gmail.com) if you've any questions.
+Please do not hesitate to ask if you have any questions.
 
 ## Quickstart
 
-- install the unit configuration file: `cp caddy@.service /etc/systemd/system`
-- reload the systemd daemon: `systemctl deamon-reload`
-- make sure to [configure](#configuration) the service unit before starting caddy
-- start caddy: `systemctl start caddy@someuser`
-- enable the service (automatically start on boot): `systemctl enable caddy@someuser`
-- the `.caddy` folder will be created inside the users home directory that runs caddy, i.e. `/home/someuser/.caddy` for `systemctl start caddy@someuser`
+- Install the unit configuration file: `cp caddy.service /etc/systemd/system/`
+- Reload the systemd daemon: `systemctl daemon-reload`
+- Make sure to [configure](#configuration) the service unit before starting caddy.
+- Start caddy: `systemctl start caddy.service`
+- Enable the service (automatically start on boot): `systemctl enable caddy.service`
+- A folder `.caddy` will be created inside the home directory of the user that runs caddy;
+  you can change that by providing an environment variable `HOME`,
+  i.e. `Environment=HOME=/var/lib/caddy` will result in `/var/lib/caddy/.caddy`.
 
 ## Configuration
 
-- do not edit the systemd unit directly, use systemd's builtin tools:
-    - `systemctl edit caddy@` to make user local modifications to the service unit
-    - `systemctl edit --full caddy@` to make system-wide modifications
-- in most cases it's enough to adapt the `ExecStart` directive:
-    - `systemctl edit caddy@`
-    - systemd needs absolute paths, therefore make sure that the path to caddy is correct
+- Do not edit the systemd unit file directly. Instead, use systemd's builtin tools:
+    - `systemctl edit caddy.service` to make user-local modifications
+    - `systemctl edit --full caddy.service` for system-wide ones
+- In most cases it is enough to override the `ExecStart` directive.
+    - systemd needs absolute paths, therefore make sure that the path to caddy is correct.
     - example:
 
 ```ini
 [Service]
-; reset the original setting
+; an empty value clears the original (and preceding) settings
 ExecStart=
 ExecStart=/usr/bin/caddy -conf="/etc/caddy/myCaddy.conf" -agree -email="my@mail.address"
 ```
 
-- to view your configuration use `systemctl cat caddy@`
-- double check the permissions of your web root path to make sure that caddy can access it as its run user and group
+- To view the resulting configuration use `systemctl cat caddy`
+- Double check permissions of your *document root* path.
+  The user caddy runs as needs to have access to it. For example:
+
+```bash
+# caddy would run as        www-data:www-data
+# serving, in this example: /var/www
+
+sudo -u www-data -g www-data -s \
+  ls -hlAS /var/www
+```
 
 ## Tips
 
-- use `log stdout` and `errors stderr` in your Caddyfile to make use of `journalctl`
-- `journalctl` is systemd's log query tool
-- lets say you want all the log entries for caddy since the last boot beginning from the last entry: `journalctl --reverse --boot --unit caddy@someuser`
-- maybe you want to follow caddys log output: `journalctl -fu caddy@someuser`
-- to send a signal to a service units main PID, e.g. let caddy reload its config: `systemctl kill --signal=USR1 caddy@someuser`
+- Use `log stdout` and `errors stderr` in your Caddyfile to utilize `journalctl`.
+- `journalctl` is systemd's log query tool.
+- Let's say you want all the log entries since the last boot, beginning from the last entry:
+  `journalctl --reverse --boot --unit caddy.service`
+- To follow caddy's log output: `journalctl -fu caddy.service`
+- Send a signal to a service unit's main PID, e.g. have caddy reload its config:
+  `systemctl kill --signal=USR1 caddy.service`
+- If you have more files that start with `caddy` – like a `caddy.timer`, `caddy.path`, or `caddy.socket` – then it is important to append `.service`.
+  Although if `caddy.service` is all you have, then you can just use `caddy` without any extension, such as in: `systemctl status caddy`