docs: place copy in codeblock

Signed-off-by: Athan <kgryte@gmail.com>

Author: kgryte

docs/contributing/zen_of_stdlib.md

@@ -22,6 +22,7 @@ limitations under the License.
 
 # Zen of stdlib
 
+```text
 Do one thing. Do it well.
 Embrace radical modularity.
 Favor composition over configuration.
@@ -56,6 +57,7 @@ Mistakes are infectious.
 Fix them early.
 
 Simple is beautiful.
+```
 
 * * *