Minor edit

Author: Robert Spigler

bip-0087.mediawiki

@@ -76,7 +76,7 @@ Each level has a special meaning, described in the chapters below.
 
 ===Purpose===
 
-Purpose is a constant set to 87' following the BIP43 recommendation.
+Purpose is a constant set to <code>87'</code> following the BIP43 recommendation.
 It indicates that the subtree of this node is used according to this specification.
 
 Hardened derivation is used at this level.