Review J letter icons (simple-icons#9638)

* Update Jameson SVG

* Update Jeep source

* Update JFrog hex

* Update JR Group hex

* Update JUnit5 source

* Fix trailing slash in jfrog source

* Update Jameson SVG

* Update Jeep svg

* Update Jeep source

* Fix Jeep SVG precision

_data/simple-icons.json

@@ -6684,8 +6684,7 @@
         {
             "title": "Jeep",
             "hex": "000000",
-            "source": "https://www.fcaci.com/x/JEEPv15",
-            "guidelines": "https://www.fcaci.com/x/JEEPv15"
+            "source": "https://commons.wikimedia.org/wiki/File:Jeep_logo.svg"
         },
         {
             "title": "Jekyll",
@@ -6744,9 +6743,9 @@
         },
         {
             "title": "JFrog",
-            "hex": "41BF47",
-            "source": "https://jfrog.com/brand-guidelines/",
-            "guidelines": "https://jfrog.com/brand-guidelines/"
+            "hex": "40BE46",
+            "source": "https://jfrog.com/brand-guidelines",
+            "guidelines": "https://jfrog.com/brand-guidelines"
         },
         {
             "title": "JFrog Bintray",
@@ -6824,7 +6823,7 @@
         },
         {
             "title": "JR Group",
-            "hex": "000000",
+            "hex": "44AF35",
             "source": "https://www.jrhokkaido.co.jp"
         },
         {
@@ -6881,7 +6880,7 @@
         {
             "title": "JUnit5",
             "hex": "25A162",
-            "source": "https://raw.githubusercontent.com/junit-team/junit5/86465f4f491219ad0c0cf9c64eddca7b0edeb86f/assets/img/junit5-logo.svg"
+            "source": "https://github.com/junit-team/junit5/blob/86465f4f491219ad0c0cf9c64eddca7b0edeb86f/assets/img/junit5-logo.svg"
         },
         {
             "title": "Jupyter",