[hostinfo] Document what this module does

src/modules/hostinfo/hostinfo.conf

@@ -0,0 +1,20 @@
+# Configuration for hostinfo
+#
+# There isn't anything to configure for the hostinfo module.
+#
+# Hostinfo puts information about the host system into Calamares
+# GlobalStorage. This information is generally unchanging. Put
+# this module somewhere early in the exec: section to pick up
+# the variables. Use a contextualprocess module later to
+# react to the values, if needed.
+#
+# GlobalStorage keys:
+#
+#   - *hostOS* the OS this module was built under; value is "Linux" or
+#       "FreeBSD" or blank.
+#   - *hostOSName* the NAME value from /etc/os-release if it exists,
+#       otherwise the same as *hostOS*.
+#   - *hostCPU* the make (brand) of the CPU, if it can be determined.
+#       Values are "Intel" or "AMD" or blank.
+---
+# There is no configuration to be done.