system/utils/README: add missing closing code block syntax (```) for echo
In markdown, code block syntax requires two of "```"s for opening and closing.
But commit missed closing for description of echo part.
This commit fixes wrong usages of ```.
@@ -334,7 +334,7 @@ Kernel Features -> Disable TinyAra interfaces -> [ ] Disable environment variabl
- Set a value which is greater than zero on CONFIG_NFILE_DESCRIPTORS.
```
Kernel Features -> Files and I/O -> Maximum number of file descriptors per task
-
+```
## free
This command shows heap information.
