fix: change branch/name-here to branch-name-here in git push commands

Closes #1202 - Improves clarity for new contributors by using
hyphen instead of slash in branch name placeholder.

Author: chinar-amrutkar

src/content/docs/how-to-contribute-to-the-codebase.mdx

@@ -218,7 +218,7 @@ Follow these steps:
 10. Next, you can push your changes to your fork:
 
     ```bash
-    git push origin branch/name-here
+    git push origin branch-name-here
     ```
 
 </Steps>

src/content/docs/how-to-setup-freecodecamp-mobile-app-locally.mdx

@@ -388,7 +388,7 @@ Follow these steps:
 10. Next, you can push your changes to your fork:
 
     ```bash
-    git push origin branch/name-here
+    git push origin branch-name-here
     ```
 
 </Steps>