Auto merge of #5882 - bundler:rubymorillo-patch-1, r=colby-swandale
Auto merge of #5882 - bundler:rubymorillo-patch-1, r=colby-swandale

Add graph re: bundle exec modifying lockfile

Hey team,

I've added a graph to the documentation that explains why bundle exec makes changes to Gemfile.lock. It was originally referenced in this issue: https://github.com/bundler/bundler/issues/5245

Thanks so much for the contribution!
To make reviewing this PR a bit easier, please fill out answers to the following questions.

### What was the end-user problem that led to this PR?

The problem was lack of clarity around why the `bundle exec` command modified the lock file. A user brought it up here: https://github.com/bundler/bundler/issues/5245 and the determination was to add it to the man page.

### What was your diagnosis of the problem?

My diagnosis was to add a graph in the "Environmental Modifications" section to explain the issue.

### What is your fix for the problem, implemented in this PR?

My fix was to update the docs! \o/

### Why did you choose this fix out of the possible options?

I chose this fix because enough users referenced it as a problem that needed to be addressed.

bundler/bundler,mvz/bundler,dilumnavanjana/bundler,mvz/bundler,bundler/bundler,dilumnavanjana/bundler