INSTALL.md clarification

Summary: Add fvcore and iopath explicitly. As mentioned in #1416.

Reviewed By: shapovalov

Differential Revision: D42451365

fbshipit-source-id: 0d8d2ead3f15dea6abef221fd5df2b4774abc83f

Author: bottler

INSTALL.md

@@ -102,6 +102,7 @@ version_str="".join([
     torch.version.cuda.replace(".",""),
     f"_pyt{pyt_version_str}"
 ])
+!pip install fvcore iopath
 !pip install --no-index --no-cache-dir pytorch3d -f https://dl.fbaipublicfiles.com/pytorch3d/packaging/wheels/{version_str}/download.html
 ```
 

packaging/linux_wheels/README.md

@@ -26,5 +26,6 @@ version_str="".join([
     torch.version.cuda.replace(".",""),
     f"_pyt{pyt_version_str}"
 ])
+!pip install fvcore iopath
 !pip install --no-index --no-cache-dir pytorch3d -f https://dl.fbaipublicfiles.com/pytorch3d/packaging/wheels/{version_str}/download.html
 ```