doc: Correct CNCF project name (#3228)

Signed-off-by: Ryota <rytswd@gmail.com>

README.md

@@ -19,7 +19,7 @@ Thanos is a set of components that can be composed into a highly available metri
 system with unlimited storage capacity, which can be added seamlessly on top of existing
 Prometheus deployments.
 
-Thanos is a [CNCF](https://www.cncf.io/) Incubation project.
+Thanos is a [CNCF](https://www.cncf.io/) Incubating project.
 
 Thanos leverages the Prometheus 2.0 storage format to cost-efficiently store historical metric
 data in any object storage while retaining fast query latencies. Additionally, it provides

website/layouts/index.html

@@ -100,7 +100,7 @@ <h2 class="heading-big text-center">Used By</h2>
             <div class="col col-sm-1 col-md-6 offset-md-3 col-lg-4 offset-lg-4 text-center">
                 <img class="img-fluid" style="max-width: 60%" src="cloud-native-computing.svg" alt="CNCF"/>
             </div>
-            <p>We are a <a href="https://cncf.io">Cloud Native Computing Foundation</a> Incubation project.</p>
+            <p>We are a <a href="https://cncf.io">Cloud Native Computing Foundation</a> Incubating project.</p>
         </div>
     </div>
 </div>