fiexd extension of pictures

Author: graydonli

docs/en/product_documents/m5stack-core/m5core_basic.md

@@ -1,6 +1,6 @@
 # M5Core BASIC
 
-<img src="assets/img/product_pics/core/basic/basic_02.jpg" alt="basic_02" width="250" height="250"> <img src="assets/img/product_pics/core/basic/basic_03.jpg" alt="basic_03" width="250" height="250"> <img src="assets/img/product_pics/core/basic/basic_04.jpg" alt="basic_04" width="65%" height="65%">
+<img src="assets/img/product_pics/core/basic/basic_02.png" alt="basic_02" width="250" height="250"> <img src="assets/img/product_pics/core/basic/basic_03.png" alt="basic_03" width="250" height="250"> <img src="assets/img/product_pics/core/basic/basic_04.png" alt="basic_04" width="65%" height="65%">
 
 * * *
 
@@ -107,11 +107,11 @@ The a Bottom board on the back of M5Core. It's designed for expanding gpio on M-
 -  Type-C USB Cable
 -  User Manual
 
-<img src="assets/img/product_pics/core/basic/basic_06.JPG" width="250" height="250"> <img src="assets/img/product_pics/core/basic/basic_07.JPG" width="250" height="250">
+<img src="assets/img/product_pics/core/basic/basic_06.png" width="250" height="250"> <img src="assets/img/product_pics/core/basic/basic_07.png" width="250" height="250">
 
-<img src="assets/img/product_pics/core/basic/basic_08.JPG" width="250" height="250"> <img src="assets/img/product_pics/core/basic/basic_09.JPG" width="250" height="250">
+<img src="assets/img/product_pics/core/basic/basic_08.png" width="250" height="250"> <img src="assets/img/product_pics/core/basic/basic_09.png" width="250" height="250">
 
-<img src="assets/img/product_pics/core/basic/basic_10.JPG" width="50%" height="50%">
+<img src="assets/img/product_pics/core/basic/basic_10.png" width="50%" height="50%">
 
 ## Related Link
 

docs/en/product_documents/m5stack-core/m5core_fire.md

@@ -167,21 +167,21 @@ https://github.com/m5stack/M5-Schematic/blob/master/Core/hardware_diff_between_m
 ### Diagram of Fire
 
 <figure>
-    <img src="assets/img/product_pics/core/fire/product_pic_fire.jpg" width="500px" height="500px">
+    <img src="assets/img/product_pics/core/fire/product_pic_fire.png" width="500px" height="500px">
 </figure>
 
 <figure>
-    <img src="assets/img/product_pics/core/fire/simple_sch_just_for_fire.jpg">
+    <img src="assets/img/product_pics/core/fire/simple_sch_just_for_fire.png">
 </figure>
 
 <figure>
-    <img src="assets/img/product_pics/core/fire/interface_fire.jpg">
+    <img src="assets/img/product_pics/core/fire/interface_fire.png">
 </figure>
 
 <figure>
-    <img src="assets/img/product_pics/core/fire/m5_fire_01.jpg" >
+    <img src="assets/img/product_pics/core/fire/m5_fire_01.png" >
 </figure>
 
 <figure>
-    <img src="assets/img/product_pics/core/fire/m5_fire_02.jpg" >
+    <img src="assets/img/product_pics/core/fire/m5_fire_02.png" >
 </figure>

docs/en/product_documents/m5stack-core/m5core_gray.md

@@ -117,17 +117,17 @@ The a Bottom board on the back of M5Core. It's designed for expanding gpio on M-
 - **[The difference between M5Cores](https://github.com/m5stack/M5-Schematic/blob/master/Core/hardware_diff_between_m5cores.md)**
 
 <figure>
-  <img src="assets/img/product_pics/core/gray/gray_01.jpg" alt="gray_01" width="500px" height="500px">
+  <img src="assets/img/product_pics/core/gray/gray_01.png" alt="gray_01" width="500px" height="500px">
 </figure>
 <figure>
-  <img src="assets/img/product_pics/core/gray/gray_02.jpg" alt="gray_02" width="500px" height="500px">
+  <img src="assets/img/product_pics/core/gray/gray_02.png" alt="gray_02" width="500px" height="500px">
 </figure>
 <figure>
-  <img src="assets/img/product_pics/core/gray/gray_03.jpg" alt="gray_03" width="500px" height="500px">
+  <img src="assets/img/product_pics/core/gray/gray_03.png" alt="gray_03" width="500px" height="500px">
 </figure>
 <figure>
-  <img src="assets/img/product_pics/core/gray/gray_04.jpg" alt="gray_04" width="65%" height="65%">
+  <img src="assets/img/product_pics/core/gray/gray_04.png" alt="gray_04" width="65%" height="65%">
 </figure>
 <figure>
-  <img src="assets/img/product_pics/core/gray/gray_05.jpg" alt="gray_05" width="65%" height="65%">
+  <img src="assets/img/product_pics/core/gray/gray_05.png" alt="gray_05" width="65%" height="65%">
 </figure>