cheatsheet: Fix misspelling of TEMPLATECONF

The existing hint would not work, as the tool expects the variable to be
called TEMPLATECONF not TEMPLATE_CONF.

Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/cheatsheet.md b/cheatsheet.md
index 530f6c0..2f9fc15 100644
--- a/cheatsheet.md
+++ b/cheatsheet.md
@@ -50,7 +50,7 @@
 ```
 rm -rf build/conf
 ```
-and running `oe-init-build-env` again (possibly with `TEMPLATE_CONF` set).
+and running `oe-init-build-env` again (possibly with `TEMPLATECONF` set).
 
 ## Useful dbus CLI tools