Change file tree headings to directory tree

src/chapter_3_2_1.md

@@ -6,7 +6,7 @@ In the case of PeachCloud, the `peach-menu` microservice subscribes to `peach-bu
 
 _Note: This module is relatively stable but is still a work-in-progress._
 
-### File Tree
+### Directory Tree
 
 ```
 .

src/chapter_3_2_2.md

@@ -6,7 +6,7 @@ OLED menu microservice module for PeachCloud. A state machine which listens for
 
 _Note: This module is a work-in-progress._
 
-### File Tree
+### Directory Tree
 
 ```
 .

src/chapter_3_2_3.md

@@ -27,7 +27,7 @@ _Note: This module is a work-in-progress._
 | `reconnect_wifi` | `iface` | Disconnect and reconnect given interface |
 | `reassociate_wifi` | `iface` | Reassociate with current AP for given interface |
 
-### File Tree
+### Directory Tree
 
 ```
 .

src/chapter_3_2_4.md

@@ -23,7 +23,7 @@ OLED microservice module for PeachCloud. Write to a 128x64 OLED display with SDD
 | `8x16` |
 | `12x16` |
 
-### File Tree
+### Directory Tree
 
 ```
 .

src/chapter_3_2_5.md

@@ -15,7 +15,7 @@ System statistics microservice module for PeachCloud. Provides a JSON-RPC wrappe
 | `mem_stats` | Memory statistics | `total`, `free`, `used` |
 | `uptime` | System uptime | `secs`, `nanos` |
 
-### File Tree
+### Directory Tree
 
 ```
 .