fix directory tree renderings

doc/manual/src/architecture/store/fso.md

@@ -19,27 +19,27 @@ Examples:
 
 - a directory with contents
 
-    /nix/store/<hash>-hello-2.10
-    ├── bin
-    │   └── hello
-    └── share
-        ├── info
-        │   └── hello.info
-        └── man
-            └── man1
-                └── hello.1.gz
+      /nix/store/<hash>-hello-2.10
+      ├── bin
+      │   └── hello
+      └── share
+          ├── info
+          │   └── hello.info
+          └── man
+              └── man1
+                  └── hello.1.gz
 
 - a directory with relative symlink and other contents
 
-    /nix/store/<hash>-go-1.16.9
-    ├── bin -> share/go/bin
-    ├── nix-support/
-    └── share/
+      /nix/store/<hash>-go-1.16.9
+      ├── bin -> share/go/bin
+      ├── nix-support/
+      └── share/
 
 - a directory with absolute symlink
 
-    /nix/store/d3k...-nodejs
-    └── nix_node -> /nix/store/f20...-nodejs-10.24.
+      /nix/store/d3k...-nodejs
+      └── nix_node -> /nix/store/f20...-nodejs-10.24.
 
 A bare file or symlink can be a root file system object.
 Examples:
@@ -53,13 +53,13 @@ Examples:
 
 - an arbitrarily symlinked file may change or not exist at all
 
-    /nix/store/<hash>-foo
-    └── foo -> /home/foo
+      /nix/store/<hash>-foo
+      └── foo -> /home/foo
 
 - if a symlink to a store path was not automatically created by Nix, it may be invalid or get invalidated when the store object is deleted
 
-    /nix/store/<hash>-bar
-    └── bar -> /nix/store/abc...-foo
+      /nix/store/<hash>-bar
+      └── bar -> /nix/store/abc...-foo
 
 Nix file system objects do not support [hard links][hardlink]:
 each file system object which is not the root has exactly one parent and one name.