docs/website: add Calian as a bronze sponsor

Calian provides a diverse set of mission-critical solutions to solve
complex challenges for customers in defence, space, health and other
critical infrastructure industries.

We thanks them for contributing to the LTS maintenance as a bronze
sponsor.

[1] https://www.calian.com/
[2] https://www.linkedin.com/company/calian/

Signed-off-by: Thomas Perale <thomas.perale@mind.be>
Signed-off-by: Julien Olivain <ju.o@free.fr>

docs/website/sponsors.html

@@ -74,6 +74,21 @@
     <div class="panel-body">
       <h3>Bronze Sponsors</h3>
       <div class="sponsors-container">
+        <div class="sponsor-entry">
+          <div class="panel panel-default panel-lts-sponsor">
+            <div class="panel-body">
+              <div class="sponsor-title">
+                <a href="https://calian.com/">
+                  <img class="img-responsive center-block" style="height: 100%;" src="images/calian-logo.png"/>
+                </a>
+              </div>
+              <div class="sponsor-body">
+                <a href="https://calian.com/">Calian</a>
+              </div>
+            </div>
+          </div>
+        </div>
+
         <div class="sponsor-entry">
           <div class="panel panel-default panel-lts-sponsor">
             <div class="panel-body">