Add README with installation instructions

README.md

@@ -1,3 +1,14 @@
+# Installation
+
+* Install hugo (if you have set up your pi with [pi-tools](https://github.com/scubbo/pi-tools),
+  this will already be done):
+  * `latestHugoVersion=$(curl -s https://api.github.com/repos/gohugoio/hugo/releases | jq -r '.[] | .tag_name' | perl -pe 's/^v//' | sort -V | tail -n 1)`
+  * `wget -q -O /tmp/hugo.deb https://github.com/gohugoio/hugo/releases/download/v${latestHugoVersion}/hugo_${latestHugoVersion}_Linux-ARM.deb`
+  * `sudo apt install /tmp/hugo.deb`
+* `git submodule init && git submodule update --recursive`
+
+# Use
+
 Content is stored in `blog/`. All `hugo` commands below should be executed from there.
 This top-level directory is just for package metadata, `README.md`, etc.