Fix typo in pqRulerScale16.png icon

Typo was introduced in 3fb80ad3.
4 jobs for !4354 with 20182-ruler-scale-typo
detached
Status Job ID Name Coverage
  Package
manual #5178562
paraview linux docker build manual
package:documentation
manual #5178561
paraview linux docker build manual
package:spack-centos7
 
  External
passed cdash-commit

passed ghostflow-branch-check-master