Update docs/pos/reference/contracts/stakingmanager.md

Co-authored-by: kmurphypolygon <149679879+kmurphypolygon@users.noreply.github.com>

Author: EmpieichO

docs/pos/reference/contracts/stakingmanager.md

@@ -182,7 +182,7 @@ function checkSignatures(
 
 Checks if a given validator is active validator for the current epoch.
 
-## Timeline Data Structure
+## Timeline data structure
 
 ```solidity
 struct State {