Makefile: fix rsvg-convert --format capitalization

On some versions of rsvg-convert, capitalized formats are unknown.

For example on CentOS Stream 9:

  $ rsvg-convert --format=Png --output=ref-manual/svg/releases.png ref-manual/svg/releases.svg
  Unknown output format.

While the same command with "png" runs fine.

On Ubuntu 22.04, both are accepted.

Switch to the un-capitalized options, compatible with all versions.

Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
(From yocto-docs rev: 8e3e562179d47553268970f49a98817abfb32df6)

Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
(cherry picked from commit cb60df269ef6329372f2676ab705134bbf2490eb)
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/documentation/Makefile b/documentation/Makefile
index 65e29713d4..07801cc2d3 100644
--- a/documentation/Makefile
+++ b/documentation/Makefile
@@ -43,11 +43,11 @@ PNGs := $(foreach dir, $(IMAGEDIRS), $(patsubst %.svg,%.png,$(wildcard $(SOURCED
 
 # Pattern rule for converting SVG to PDF
 %.pdf : %.svg
-        $(SVG2PDF) --format=Pdf --output=$@ $<
+        $(SVG2PDF) --format=pdf --output=$@ $<
 
 # Pattern rule for converting SVG to PNG
 %.png : %.svg
-        $(SVG2PNG) --format=Png --output=$@ $<
+        $(SVG2PNG) --format=png --output=$@ $<
 
 clean:
         @rm -rf $(BUILDDIR) $(PNGs) $(PDFs) poky.yaml sphinx-static/switchers.js releases.rst