Update cheatsheets

sldtoppm

@@ -0,0 +1,17 @@
+---
+syntax: markdown
+tags: [tldr, common]
+source: https://github.com/tldr-pages/tldr.git
+---
+# sldtoppm
+
+> Convert an AutoCAD slide file to a PPM image.
+> More information: <https://netpbm.sourceforge.net/doc/sldtoppm.html>.
+
+- Convert an SLD file to a PPM image:
+
+`sldtoppm {{path/to/input.sld}} > {{path/to/output.ppm}}`
+
+- Compensate for non-square pixels by scaling the width of the image:
+
+`sldtoppm -adjust {{path/to/input.sld}} > {{path/to/output.ppm}}`