Fix formatting in Assamese translation

[khushig159]

Removed extra closing code block lines in README.assamese.md so the file displays correctly.

Fixes #107870

My first open source contribution , thank you so much for this amazing project!

[Sharl0tteIsTaken]

Hello @rammba,

The issue #107870 this PR is trying to address has been resolved in PR #107894, I'm inclined to close this PR. What do you think?
Both #107870 and #107894 can be closed and merged after been reviewed by @Roshanjossey.

[rammba]

Hello @Sharl0tteIsTaken, since #107894 it's already done and just waiting for merge, we can close this.

[Sharl0tteIsTaken]

@rammba, Thank you.

@khushig159, The issue this PR is trying to address has been resolved in PR #107894.
If you want to work on issues, you can check other issues with label help wanted. Here is a link for your convenience:
https://github.com/firstcontributions/first-contributions/issues?q=is%3Aissue%20state%3Aopen%20label%3A%22help%20wanted%22

Closing.