Add manpages for eg25-manager and it's config file

data/eg25-manager.8.scd

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+eg25-manager(8)
+
+# NAME
+eg25-manager - a daemon for managing the Quectel EG25 modem found on the
+Pine64 PinePhone.
+
+# SYNOPSIS
+*eg25-manager* [-v] [-c config_file]
+
+# OPTIONS
+*-v*
+	Show the version number and quit.
+*-c*
+	User configuration file, defaults to the device configuration file in
+	/etc/eg25-manager.
+
+# FILES
+Configurations are loaded from:
+	- *@eg25_confdir@/<compatible>.toml*: User-provided overrides (optional)
+	- *@eg25_datadir@/<compatible>.toml*: Default configuration (required)
+
+eg25-manager will search these folders for files named after the value of the
+compatible device-tree property (with the .toml file extension) and use the
+first matching file in each directory. If no matching default configuration is
+found, eg25-manager will exit with an error message.
+
+Values from the user-provided overrides will take priority over values stored in
+the default configuration. Only changed values must be stored as user overrides,
+so eg25-manager can fall back to the default configuration as often as possible.
+
+The file names eg25-manager will check can be listed using:
+```
+xargs -0 printf '%s.toml\\n' < /proc/device-tree/compatible
+```
+
+# SEE ALSO
+*eg25-manager*(5) *ModemManager*(8) *ofono*(8)