First draft of new setup instructions

Author: lockshaw

.editorconfig

@@ -20,3 +20,7 @@ indent_size = 4
 [*.toml]
 indent_style = space
 indent_size = 2
+
+[*.md]
+indent_style = space
+indent_size = 2

.github/PULL_REQUEST_TEMPLATE.md

@@ -9,7 +9,3 @@ Linked Issues:
 
 Issues closed by this PR:
 - Closes #
-
-**Before merging:**
-
-- [ ] Did you update the [flexflow-third-party](https://github.com/flexflow/flexflow-third-party) repo, if modifying any of the Cmake files, the build configs, or the submodules?