fix: enable persisted queries when option is true, resolves #240 (#242)

* fix: enable persisted queries when option is `true`, resolves #240

* fix: do not require an `enabled` property to avoid conflicts

Author: nether-cat

docs/guide/configuration.md

@@ -13,8 +13,8 @@ createApolloClient({
   // Enable this if you use Query persisting with Apollo Engine
   persisting: false,
   // Or, advanced persisting options, see https://github.com/apollographql/apollo-link-persisted-queries#options
+  // Example:
   // persisting: {
-  //  enabled: false,
   //  generateHash: query => sha256()
   //    .update(print(query))
   //    .digest('hex'),

graphql-client/src/index.js

@@ -103,8 +103,9 @@ export function createApolloClient ({
       let persistingOpts = {}
       if (typeof persisting === 'object' && persisting != null) {
         persistingOpts = persisting
+        persisting = true
       }
-      if (persistingOpts.enabled) {
+      if (persisting === true) {
         link = createPersistedQueryLink(persistingOpts).concat(link)
       }
     }