Makefile: Add missing doc on pngs in docs

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

diff --git a/Makefile b/Makefile
index 8eeef04b51a606c361aaaed619f3d31ebc46f78e..0782e9c956552ac6a5a87b58df3b236cf7cec343 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -232,7 +232,7 @@ doc-sphinx: docs/html/index.html
        @echo 'Documentation can now be found here:'
        @echo '  file://$(PWD)/$<'
 
-docs/html/index.html: docs/conf.py $(wildcard docs/*.md docs/*.rst)
+docs/html/index.html: docs/conf.py $(wildcard docs/*.md docs/*.rst docs/*.png)
        $(SPHINXBUILD) -M html docs docs $(SPHINXOPTS)
 
 #---------- wasm ----------