Add platform buttons

lib/constants.dart

@@ -36,6 +36,9 @@ const String kGoogleStoreUrl = 'https://play.google.com/apps/testing/com.invoice
 const String kMacOSUrl = 'http://download.invoiceninja.com/macos';
 const String kLinuxUrl = 'http://download.invoiceninja.com/linux';
 
+const String kApiDocsURL = 'https://app.swaggerhub.com/apis/invoiceninja/invoiceninja';
+const String kZapierURL = 'https://zapier.com/developer/public-invite/95884/5e4368b9efb9d377dc0a0b0465b7c1a7';
+
 const String kCapterralUrl = 'https://www.capterra.com/p/145215/Invoice-Ninja/';
 const String kCronsHelpUrl =
     'https://invoiceninja.github.io/selfhost.html#cron-configuration';

lib/ui/settings/account_management.dart

@@ -18,6 +18,7 @@ import 'package:invoiceninja_flutter/utils/dialogs.dart';
 import 'package:invoiceninja_flutter/utils/formatting.dart';
 import 'package:invoiceninja_flutter/utils/icons.dart';
 import 'package:invoiceninja_flutter/utils/localization.dart';
+import 'package:material_design_icons_flutter/material_design_icons_flutter.dart';
 import 'package:url_launcher/url_launcher.dart';
 
 class AccountManagement extends StatefulWidget {
@@ -260,6 +261,25 @@ class _AccountOverview extends StatelessWidget {
                 ),
               ),
             ])),
+        Padding(
+            padding: const EdgeInsets.all(16),
+            child: Row(children: [
+              Expanded(
+                child: AppButton(
+                  label: localization.apiDocs.toUpperCase(),
+                  iconData: MdiIcons.bookshelf,
+                  onPressed: () => launch(kApiDocsURL),
+                ),
+              ),
+              SizedBox(width: kGutterWidth),
+              Expanded(
+                child: AppButton(
+                  label: 'Zapier',
+                  iconData: MdiIcons.cloud,
+                  onPressed: () => launch(kZapierURL),
+                ),
+              ),
+            ])),
         Padding(
           padding: const EdgeInsets.symmetric(vertical: 16, horizontal: 16),
           child: ListDivider(),

lib/utils/i18n.dart

@@ -283,6 +283,7 @@ mixin LocalizationsProvider on LocaleCodeAware {
       'removed_webhooks': 'Successfully removed :value webhooks',
       'restored_webhooks': 'Successfully restored :value webhooks',
       'api_tokens': 'API Tokens',
+      'api_docs': 'API Docs',
       'search_tokens': 'Search :count Tokens',
       'search_token': 'Search 1 Token',
       'token': 'Token',
@@ -4690,6 +4691,8 @@ mixin LocalizationsProvider on LocaleCodeAware {
 
   String get apiTokens => _localizedValues[localeCode]['api_tokens'] ?? '';
 
+  String get apiDocs => _localizedValues[localeCode]['api_docs'] ?? '';
+
   String get apiWebhooks => _localizedValues[localeCode]['api_webhooks'] ?? '';
 
   String get cronsNotEnabled =>