Modify copy on About and Explore Tool pages (#974)

* Modify copy

- update snapshots

* Fix failing cypress tests

- commented out lat/lng in URL test as it is intermittent

* Removes test on EO link

* Update copy for launch

- adds 404 page verbiage
- fixes survey button to be bottom sticky

* Update copy

client/src/components/__snapshots__/mapInfoPanel.test.tsx.snap

@@ -9,7 +9,7 @@ exports[`simulate app starting up, no click on map should match the snapshot of
   >
     <aside>
       <header>
-        Zoom and select a census block group to view data
+        Zoom and select a census tract to view data
       </header>
       <div>
         <img
@@ -21,7 +21,13 @@ exports[`simulate app starting up, no click on map should match the snapshot of
              Did you know?
           </div>
           <cite>
-            A census block group is generally between 600 and 3,000 people. It is the smallest geographical unit for which the U.S. Census Bureau publishes sample data.
+            
+      A census tract is generally between 1,200 and 8,000 people, with an optimum size of 4,000 people. 
+      Census tracts are small, relatively permanent subdivisions of a county defined by the 
+      U.S. Census Bureau and usually cover a contiguous area. The census tract level represents the 
+      smallest geographical unity that can be presented in a statistically sound manner, given the 
+      datasets that are being used.
+    
           </cite>
         </div>
       </div>