Release v1.6.0 (#324)

* Update version and changelog for v1.6.0
* Update docs
diff --git a/docs/dyn/content_v2.datafeeds.html b/docs/dyn/content_v2.datafeeds.html
index e1c5769..7af9439 100644
--- a/docs/dyn/content_v2.datafeeds.html
+++ b/docs/dyn/content_v2.datafeeds.html
@@ -79,25 +79,25 @@
 <p class="firstline">A description of how to use this function</p>
 <p class="toc_element">
   <code><a href="#delete">delete(merchantId, datafeedId, dryRun=None)</a></code></p>
-<p class="firstline">Deletes a datafeed from your Merchant Center account.</p>
+<p class="firstline">Deletes a datafeed from your Merchant Center account. This method can only be called for non-multi-client accounts.</p>
 <p class="toc_element">
   <code><a href="#get">get(merchantId, datafeedId)</a></code></p>
-<p class="firstline">Retrieves a datafeed from your Merchant Center account.</p>
+<p class="firstline">Retrieves a datafeed from your Merchant Center account. This method can only be called for non-multi-client accounts.</p>
 <p class="toc_element">
   <code><a href="#insert">insert(merchantId, body, dryRun=None)</a></code></p>
-<p class="firstline">Registers a datafeed with your Merchant Center account.</p>
+<p class="firstline">Registers a datafeed with your Merchant Center account. This method can only be called for non-multi-client accounts.</p>
 <p class="toc_element">
   <code><a href="#list">list(merchantId, pageToken=None, maxResults=None)</a></code></p>
-<p class="firstline">Lists the datafeeds in your Merchant Center account.</p>
+<p class="firstline">Lists the datafeeds in your Merchant Center account. This method can only be called for non-multi-client accounts.</p>
 <p class="toc_element">
   <code><a href="#list_next">list_next(previous_request, previous_response)</a></code></p>
 <p class="firstline">Retrieves the next page of results.</p>
 <p class="toc_element">
   <code><a href="#patch">patch(merchantId, datafeedId, body, dryRun=None)</a></code></p>
-<p class="firstline">Updates a datafeed of your Merchant Center account. This method supports patch semantics.</p>
+<p class="firstline">Updates a datafeed of your Merchant Center account. This method can only be called for non-multi-client accounts. This method supports patch semantics.</p>
 <p class="toc_element">
   <code><a href="#update">update(merchantId, datafeedId, body, dryRun=None)</a></code></p>
-<p class="firstline">Updates a datafeed of your Merchant Center account.</p>
+<p class="firstline">Updates a datafeed of your Merchant Center account. This method can only be called for non-multi-client accounts.</p>
 <h3>Method Details</h3>
 <div class="method">
     <code class="details" id="custombatch">custombatch(body, dryRun=None)</code>
@@ -202,7 +202,7 @@
 
 <div class="method">
     <code class="details" id="delete">delete(merchantId, datafeedId, dryRun=None)</code>
-  <pre>Deletes a datafeed from your Merchant Center account.
+  <pre>Deletes a datafeed from your Merchant Center account. This method can only be called for non-multi-client accounts.
 
 Args:
   merchantId: string, A parameter (required)
@@ -213,7 +213,7 @@
 
 <div class="method">
     <code class="details" id="get">get(merchantId, datafeedId)</code>
-  <pre>Retrieves a datafeed from your Merchant Center account.
+  <pre>Retrieves a datafeed from your Merchant Center account. This method can only be called for non-multi-client accounts.
 
 Args:
   merchantId: string, A parameter (required)
@@ -254,7 +254,7 @@
 
 <div class="method">
     <code class="details" id="insert">insert(merchantId, body, dryRun=None)</code>
-  <pre>Registers a datafeed with your Merchant Center account.
+  <pre>Registers a datafeed with your Merchant Center account. This method can only be called for non-multi-client accounts.
 
 Args:
   merchantId: string, A parameter (required)
@@ -327,7 +327,7 @@
 
 <div class="method">
     <code class="details" id="list">list(merchantId, pageToken=None, maxResults=None)</code>
-  <pre>Lists the datafeeds in your Merchant Center account.
+  <pre>Lists the datafeeds in your Merchant Center account. This method can only be called for non-multi-client accounts.
 
 Args:
   merchantId: string, The ID of the managing account. (required)
@@ -389,7 +389,7 @@
 
 <div class="method">
     <code class="details" id="patch">patch(merchantId, datafeedId, body, dryRun=None)</code>
-  <pre>Updates a datafeed of your Merchant Center account. This method supports patch semantics.
+  <pre>Updates a datafeed of your Merchant Center account. This method can only be called for non-multi-client accounts. This method supports patch semantics.
 
 Args:
   merchantId: string, A parameter (required)
@@ -463,7 +463,7 @@
 
 <div class="method">
     <code class="details" id="update">update(merchantId, datafeedId, body, dryRun=None)</code>
-  <pre>Updates a datafeed of your Merchant Center account.
+  <pre>Updates a datafeed of your Merchant Center account. This method can only be called for non-multi-client accounts.
 
 Args:
   merchantId: string, A parameter (required)