docs: eliminate extra work (vuejs#1442)

"You can do achieve this" -> "You can achieve this"

Author: dcrall

docs/guide/modules.md

@@ -295,7 +295,7 @@ Dynamic module registration makes it possible for other Vue plugins to also leve
 
 You can also remove a dynamically registered module with `store.unregisterModule(moduleName)`. Note you cannot remove static modules (declared at store creation) with this method.
 
-It may be likely that you want to preserve the previous state when registering a new module, such as preserving state from a Server Side Rendered app. You can do achieve this with `preserveState` option: `store.registerModule('a', module, { preserveState: true })`
+It may be likely that you want to preserve the previous state when registering a new module, such as preserving state from a Server Side Rendered app. You can achieve this with `preserveState` option: `store.registerModule('a', module, { preserveState: true })`
 
 ### Module Reuse