How can I convert STL files into PDF drawings?
I've had good results with using the free web-based program known as Onshape which allows you to import/create 3D models. One of the features built into Onshape is a drawing tab. You can select the views desired or use a standard layout, as well as add dimensions to the individual drawing views.



This image above was of a model created in and exported from Tinkercad. No dimensions have been added in this example, but it's available as part of the software. Being browser based, the program will work for any platform.

In order to make this answer more accurate, I attempted to duplicate the results shown in the drawing.

I've discovered that I used Fusion 360 to import the STL. The next step involved turning off history feature, then converting the STL to BREP. Once in BREP form, the no-longer-STL file can be exported as .step, which is accepted by Onshape.

Fusion 360 is a free-to-hobbyists program, but does not run in a browser. There may be other programs which will convert STL to .step and there may even be a browser converter-specific site to accomplish this.

I recognize that this is a convoluted solution, but it's not particularly burdensome, overall.