Update cheatsheets

ppmtoyuv

@@ -0,0 +1,13 @@
+---
+syntax: markdown
+tags: [tldr, common]
+source: https://github.com/tldr-pages/tldr.git
+---
+# ppmtoyuv
+
+> Convert a PPM image to an Abekas YUV file.
+> More information: <https://netpbm.sourceforge.net/doc/ppmtoyuv.html>.
+
+- Read a PPM image from the input file, convert it to an Abekas YUV image and store it in the specified output file:
+
+`ppmtoyuv {{path/to/input_file.ppm}} > {{path/to/output_file.yuv}}`