refactor: move images of the "bonita-overview" module (#2917)

The images were stored in the Antora legacy folder (assets/images) and
included an extra "images" sub-folder.
All images are now in the "images" folder of the module, which is the
standard Antora folder.


Covers
bonitasoft/bonita-documentation-site#620

modules/bonita-overview/pages/bonita-studio.adoc

@@ -31,8 +31,7 @@ Bonita Studio is not intended for any use other than development. As a consequen
 
 == Architecture overview
 
-image:images/getting-started-tutorial/what-is-bonita/architecture-bonita-studio.png[Bonita Studio architecture]
-// {.img-responsive .img-thumbnail}
+image:architecture-bonita-studio.png[Bonita Studio architecture]
 
 
 [.card-section]
@@ -68,7 +67,7 @@ xref:setup-dev-environment:setup-dev-environment-index.adoc[[.card-title]#Develo
 xref:ROOT:update-studio.adoc[[.card-title]#Update Bonita Studio# [.card-body.card-content-overflow]#pass:q[The recommended flow to update the development environment]#]
 --
 
-== image:images/troubleshooting.png[troubleshooting-icon] Troubleshooting
+== image:troubleshooting.png[troubleshooting-icon] Troubleshooting
 
 === Log files
 
@@ -153,7 +152,7 @@ If you need another version:
 === java.security.cert.CertificateException: No subject alternative DNS name matching github-releases.githubusercontent.com found.
 
 ****
-Bonita Studio needs to retrieve some remote assets from Github. +
+Bonita Studio needs to retrieve some remote assets from GitHub. +
 *Symptom:* +
 The download of those assets fails with the above exception. +
 *Potential cause:* +

modules/bonita-overview/pages/project-structure.adoc

@@ -8,7 +8,7 @@ This page defines the elements used to compose a Bonita Automation project.
 Bonita Automation projects are based on processes but also data, user interfaces, identity management and extensions.
 
 [.text-center]
-image:images/BonitaProjectElements.png[]
+image:bonita-project-elements.png[]
 
 [NOTE]
 ====

modules/bonita-overview/pages/ui-designer-overview.adoc

@@ -24,7 +24,7 @@ A row is a mechanism for aligning widgets, from top left to bottom right. When y
 
 To move or delete a row, position your mouse in the row, and the row toolbar is displayed.
 
-image::images/images-6_0/row-over.png[row toolbar]
+image::uid-row-over.png[row toolbar]
 
 Use the controls in the toolbar to move the row up or down, or to delete it.
 
@@ -44,7 +44,7 @@ There are different types of containers:
 
 Once a container is added to the page, it contains a row. Therefore, widgets can be dropped in a container row or directly on a whiteboard row. In this example, you can see a container with four rows.
 
-image::images/images-6_0/row-normal.png[A 4 row container]
+image::uid-row-normal.png[A 4 row container]
 
 The behavior of a page is determined by the widget properties. Any property you configure for a container is applied to all widgets in the container unless you override it with a widget-specific value.
 
@@ -157,7 +157,7 @@ Oops, some artifacts from the UI Designer got corrupted in your git repository!
 
 The UI Designer has a log file that you can consult, either from menu:Bonita Studio[Help > Bonita UI-Designer log] menu:
 
-image:images/ui-designer-troubleshooting/uid-logs.png[Open UI Designer log from the Studio]
+image:uid-logs.png[Open UI Designer log from the Studio]
 
 Or from your file system here: `STUDIO_HOME/workspace/.metadata/.plugins/org.bonitasoft.studio.designer/.extract/logs/ui-designer.log`. +
 When reading the log file, you see this kind of error: +