update logo/run icon path in README

platform/android/README.md

@@ -12,7 +12,7 @@ using [Gradle](https://gradle.org/) as a build system.
 
 ## Artwork license
 
-[`logo.png`](logo.png) and [`run_icon.png`](run_icon.png) are licensed under
+[`logo.svg`](export/logo.svg) and [`run_icon.svg`](export/run_icon.svg) are licensed under
 [Creative Commons Attribution 3.0 Unported](https://developer.android.com/distribute/marketing-tools/brand-guidelines#android_robot)
 per the Android logo usage guidelines:
 

platform/linuxbsd/README.md

@@ -14,7 +14,7 @@ used by this platform.
 
 ## Artwork license
 
-[`logo.png`](logo.png) is derived from the [Linux logo](https://isc.tamu.edu/~lewing/linux/):
+[`logo.svg`](export/logo.svg) is derived from the [Linux logo](https://isc.tamu.edu/~lewing/linux/):
 
 > Permission to use and/or modify this image is granted provided you acknowledge me
 > <[email protected]> and [The GIMP](https://isc.tamu.edu/~lewing/gimp/)

platform/web/README.md

@@ -17,6 +17,6 @@ this platform such as the html shell (web page).
 
 ## Artwork license
 
-[`logo.png`](logo.png) and [`run_icon.png`](run_icon.png) are licensed under
+[`logo.svg`](export/logo.svg) and [`run_icon.svg`](export/run_icon.svg) are licensed under
 [Creative Commons Attribution 3.0 Unported](https://www.w3.org/html/logo/faq.html#how-licenced)
 per the HTML5 logo usage guidelines.