Updated SC2155 (markdown)

SC2155.md

@@ -6,20 +6,20 @@
 export foo="$(mycmd)"
 ```
 
-### Correct code:
+#### Correct code:
 
 ```sh
 foo="$(mycmd)"
 export foo
 ```
 
-### Rationale:
+#### Rationale:
 
 In the original code, the return value of `mycmd` is ignored, and `export` will instead always return true. This may prevent conditionals, `set -e` and traps from working correctly.
 
 When first marked for export and assigned separately, the return value of the assignment will be that of `mycmd`. This avoids the problem.
 
-### Exceptions:
+#### Exceptions:
 
 If you intend to ignore the return value of an assignment, you can either ignore this warning or use
 
@@ -36,14 +36,14 @@ Shellcheck does not warn about `export foo=bar` because `bar` is a literal and n
 local foo="$(mycmd)"
 ```
 
-### Correct code:
+#### Correct code:
 
 ```sh
 local foo
 foo=$(mycmd)
 ```
 
-### Rationale
+#### Rationale
 
 The exit status of the command is overridden by the exit status of the creation of the local variable. For example:
 
@@ -59,14 +59,14 @@ foo
 readonly foo="$(mycmd)"
 ```
 
-### Correct code:
+#### Correct code:
 
 ```sh
 foo="$(mycmd)"
 readonly foo
 ```
 
-### Word splitting and quoting issue with dash, maybe others
+#### Word splitting and quoting issue with dash, maybe others
 
 A serious quoting problem with dash is another reason to declare and assign separately. Dash is the [default, `/bin/sh` shell on Ubuntu](https://wiki.ubuntu.com/DashAsBinSh). More specifically, dash version 0.5.8-2.10 and others cannot run this code:
 ```sh