Added tutorial section on extending docker image

[ash-olakangal]

Description:
While following the OpenRISC tutorial, I noticed the Docker environment lacks a text editor by default. This addition provides steps to create a custom Dockerfile to include Vim.

I also encountered a few missing dependency errors while running hello world and compiling with gcc, so I also added these libraries in case the user also sees missing dependencies. (Separate issue tracked here: stffrdhrn/or1k-docker-images#2 (comment))

Changes:
Added a section on "Extending the docker image" to images.md.
Verified Markdown rendering and list numbering locally using jekyll and bundle.

[stffrdhrn]

Thanks for you patch, please find my comments.

[stffrdhrn]

Why would this be needed? If gcc is not working then there is a uig with the docker image we should fix. Do you have a case where this happens?

[ash-olakangal]

You're right, ideally, we should be fixing this in the image itself. I'll open a separate issue in the image.

In the meantime, let me know if I should remove this step or keep this while we fix the image.

FYI the details are:

The issue is seen when running the outlined steps for simulator environment, while running the hello world example.

amo@pop-os:~/Desktop/openRISC$ docker pull stffrdhrn/or1k-sim-env
Using default tag: latest
latest: Pulling from stffrdhrn/or1k-sim-env
Digest: sha256:fdc2c5c84804f6497fa8eccdf1b1de21684678076be330d1280f2cf10445f64b
Status: Image is up to date for stffrdhrn/or1k-sim-env:latest
docker.io/stffrdhrn/or1k-sim-env:latest

amo@pop-os:~/Desktop/openRISC$ docker run -it --rm stffrdhrn/or1k-sim-env
root@7696817a20cc:/tmp# cat <<EOF >hello.c
#include <stdio.h>

int main() {
    puts("Hello\n");
    return 0;
}
EOF

root@7696817a20cc:/tmp# ls
hello.c

root@7696817a20cc:/tmp# or1k-elf-gcc hello.c -o hello
/opt/or1k/or1k-elf/bin/../libexec/gcc/or1k-elf/15.1.0/cc1: error while loading shared libraries: libmpc.so.3: cannot open shared object file: No such file or directory

root@7696817a20cc:/tmp# or1k-elf-gcc --version
or1k-elf-gcc (GCC) 15.1.0
Copyright (C) 2025 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[stffrdhrn]

Definitely the original image needs to be fixed. We should remove this section from the docs and fix the original image. Do you want to do that?

[ash-olakangal]

Sounds good. I'll take up the fix for docker image, and also update the PR to remove the 5th step in a while.

[ash-olakangal]

1. Opened a new issue to track the fix needed in docker image. Taking up the task.

2. Addressed the review comment to remove the 5th step with the latest commit.

If there's anything else, please let me know. If not then, I think we are good to push the changes. Also updated the main comment on the PR.

[stffrdhrn]

Can you squash this commit with the previous commit? We do not need the history of this to stay in the git tree.

[ash-olakangal]

Yep, Done!

[stffrdhrn]

Thank you