docs/website: add Texas Instrument as a gold sponsor

Texas Instrument is a semiconductor company that designs, manufactures
and sells analog and embedded processing chips for markets such as
industrial, automotive, personal electronics, enterprise systems and
communications equipment [1][2].

Thank you for sponsoring LTS maintenance !

[1] https://www.ti.com/
[2] https://www.linkedin.com/company/texas-instruments

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

docs/website/sponsors.html

@@ -47,7 +47,20 @@
 	    </div>
 	  </div>
 	</div>
-
+        <div class="sponsor-entry">
+          <div class="panel panel-default panel-lts-sponsor">
+            <div class="panel-body">
+              <div class="sponsor-title">
+                <a href="https://www.ti.com/">
+                  <img class="img-responsive" src="images/ti-logo.png"/>
+                </a>
+              </div>
+              <div class="sponsor-body">
+                <a href="https://www.ti.com">Texas Instruments</a>
+              </div>
+            </div>
+          </div>
+        </div>
     </div>
     </div>