Update .gitignore

Adding new ".sf/" folder to gitignore

Author: ImJohnMDaniel

.gitignore

@@ -37,6 +37,7 @@ IlluminatedCloud/
 
 # SFDX Related
 .sfdx/
+.sf/
 sfdx-source/common-base/main/default/
 sfdx-source/untracked/
 .execanon
@@ -48,4 +49,4 @@ package-lock.json
 
 
 sfdx-source/group*
-research/
+research/