Unable to add all the files to git downloaded via composer

Question

I am using imgix module in drupal which is dependent on composer. When I run command drush composer-manage install, I can see imgix-php (a library of imgix) is downloaded in vendor directory. I have setup everything correctly and it works well in my localhost. Now I want to push them into github. I can see none of file of imgix-php is added in git and it is emty in github. Then I have see there is a file .gitignore in imgix-php where vendor is written. However, I have commented it out. But unable to add any files of imgix-php. If I commented out the line vendor of .gitignore and check the status, it shows me as:

On branch staging
Your branch is up-to-date with 'origin/staging'.
Changes not staged for commit:
(use "git add <file>..." to update what will be committed)
(use "git checkout -- <file>..." to discard changes in working directory)
(commit or discard the untracked or modified content in submodules)

modified:   sites/all/vendor/imgix/imgix-php (modified content)

no changes added to commit (use "git add" and/or "git commit -a")

Could tell me someone why I can't add them.

Answer 1

Have you actually added the imgix-php files after you commented the .gitignore file, using

git add /path/to/folder/* 

or

git add --all /path/to/folder 

?