diff --git a/doc/img1.png b/doc/img/img1.png
similarity index 100%
rename from doc/img1.png
rename to doc/img/img1.png
diff --git a/doc/img2.png b/doc/img/img2.png
similarity index 100%
rename from doc/img2.png
rename to doc/img/img2.png
diff --git a/doc/img3.png b/doc/img/img3.png
similarity index 100%
rename from doc/img3.png
rename to doc/img/img3.png
diff --git a/doc/img4.png b/doc/img/img4.png
similarity index 100%
rename from doc/img4.png
rename to doc/img/img4.png