images: Fix quality

Signed-off-by: Norbert Kamiński <norbert.kaminski@3mdeb.com>

docs/common-coreboot-docs/checkbox.md

@@ -64,7 +64,7 @@ perform the following steps:
         it.
     - Restart your system for changes to take effect.
 
-![](../images/checkbox_aut_login.jpg)
+![](../images/checkbox_aut_login.png)
 
 ## Download and install Checkbox
 

docs/ecosystem/overview.md

@@ -5,7 +5,7 @@
 Dasharo ecosystem contain multiple components on various levels of
 organization. This section overview role of every component.
 
-![](../images/ecosystem_overview.jpg)
+![](../images/ecosystem_overview.png)
 
 * Open Source Firmware Community - semi-organised collections of contributors
   to projects related to embedded firmware. Dasharo project contributors are

docs/osf-trolling-list/jsm_documentation.md

@@ -36,9 +36,9 @@ To add a new request using the web service:
 3. When you are ready to send the request, click Send. Your request is created
    and awaits our response.
 
-![](../images/jsm_add_request.jpg)
+![](../images/jsm_add_request.png)
 
-![](../images/jsm_view_requests.jpg)
+![](../images/jsm_view_requests.png)
 
 ### Raising requests using email
 
@@ -64,7 +64,7 @@ also receive information on which requests will be resolved in the next release.
 
 The diagram below presents what the workflow of JSM requests looks like.
 
-![](../images/jsm_workflow.jpg)
+![](../images/jsm_workflow.png)
 
 * `Open` - your request is created and visible for us, but we didn't start
 working on it yet.