README.md: Change an `out of tree' to `out-of-tree'

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/README.md b/README.md
index 7b9b9e331379c333cfb9a6b2b521a96d1a006cc3..aeec8deb0bf30092ece9b9e3468437e9e49dbdeb 100644 (file)
--- a/README.md
+++ b/README.md
@@ -516,7 +516,7 @@ Limitations and bugs
     add an entry to `@subcmd_props` in the source, or use
     [`--subcommand-props`](#subcommand_props).
 
-  * Out of tree builds require a unified filesystem view: eg, different
+  * Out-of-tree builds require a unified filesystem view: eg, different
     users on the same host, NFS, or something.
 
     Specifically, the invocation and build execution environments must