Built-in documentation text width in Lighthouse book (#5394)

* Adjust width

* Commit changes

* Trigger Build

book/src/help_bn.md

@@ -490,4 +490,5 @@ OPTIONS:
             Specify a weak subjectivity checkpoint in `block_root:epoch` format to verify the node's sync against. The
             block root should be 0x-prefixed. Note that this flag is for verification only, to perform a checkpoint sync
             from a recent state use --checkpoint-sync-url.
-```
+```
+<style> .content main {max-width:88%;} </style>