docs: Add syntax highlighting to more code blocks

Added language tags to more code blocks in the documentation to enable
syntax highlighting.

docs/blog/2021-01-27-zmk-sotf-4.md

@@ -25,7 +25,7 @@ The initial [combos](/docs/features/combos) work has landed! The amazing [okke-f
 
 An example, that would send the `ESC` keycode when pressing both the first and second positions on your keyboard:
 
-```
+```dts
 / {
     combos {
         compatible = "zmk,combos";
@@ -46,13 +46,13 @@ Combos currently are "global", and not scoped to a given active layer. There is
 
 [okke-formsma] also contributed the initial "sticky keys" behavior, which can be used for functionality sometimes called "one shot mods" or "one shot layers". In your keymap, this would like like:
 
-```
+```dts
 &sk LEFT_CONTROL
 ```
 
 for a sticky key/modifier, or:
 
-```
+```dts
 &sl NAV
 ```
 
@@ -68,7 +68,7 @@ This is most frequently used when using multiple core base layers with different
 
 [okke-formsma] added an implementation of the "Grave Escape" behavior, developing a more generic "mod-morph" behavior to do so. Adding
 
-```
+```dts
 &gresc
 ```