Add a detail to the installation instructiions.

diff --git a/INSTALL.adoc b/INSTALL.adoc
index 683e2f0b8ab2847f53caa37c7b597f5051f89fb1..5184d6bc1201fc14a14b728ff4c3d00a7b408a50 100644 (file)
--- a/INSTALL.adoc
+++ b/INSTALL.adoc
@@ -21,3 +21,5 @@ You can also use pip to install PyYAML: `pip3 install PyYAML`.
 4. Optionally run a regression test on the code with `make check`.
 
 5. Run `./advent` to play.
+
+6. If you want to buld the documentation you will need asciidoctor.