Add initial configs for obsidian and copy logic for files

obsidian seems to only have a per-vault config approach, so my approach
is to define settings within .config/obsidian, then copy to vault dirs

src_files/.config/obsidian/hotkeys.json

@@ -0,0 +1,16 @@
+{
+  "markdown:toggle-preview": [
+    {
+      "modifiers": [
+        "Mod"
+      ],
+      "key": "E"
+    },
+    {
+      "modifiers": [
+        "Alt"
+      ],
+      "key": "R"
+    }
+  ]
+}