RENDER.md: serial number does not show up in markdown

Summary: Formatting issues with markdown text on GitHub was causing string `<serial_number>` to disappear inside `<pre>` clause.

Reviewed By: fbriggs

Differential Revision: D4763235

fbshipit-source-id: 8a0e5b63c4b5861cd1ede4bf6b4cc6ea835b6429

surround360_render/RENDER.md

@@ -24,12 +24,12 @@ render
 └── config
     ├── camera_rig.json
     └── isp
-      └── <serial_number>.json
+      └── <i>serial_number</i>.json
 </pre>
 
 It is strongly recommended that the steps in CALIBRATION.md are followed in other to create customized files for each camera. These are:
 
-- config/isp/<serial_number>.json: output of color calibration and optical vignetting calibration
+- config/isp/*serial_number*.json: output of color calibration and optical vignetting calibration
 - config/camera_rig.json: output of geometric calibration
 
 If an older version of the software that did not have geometric calibration steps in CALIBRATION.md is used, the software will expect these files instead: