Update DOC.md Troubleshooting section

[kylefhartzenberg]

Pull request addresses #979 by adding an explanation regarding the behaviour of snippet expansion when multiple snippets can potentially expand at the current buffer-position.

The explanation was appended to the Troubleshooting section of the documentation given that snippet priority is already discussed prior, and the intent is to make users aware of potentially "unexpected" behaviour when reordering snippets that share similar triggers.

[L3MON4D3]

Ah, nice!
The existing troubleshooting-section is specific to the loaders, I don't think general advice like priority should be in there.

Could you instead create a toplevel-section on troubleshooting, move the content from loaders/troubleshooting to troubleshooting/adding snippets/loaders and put the new advice into its own subsection, troubleshooting/adding snippets/general? I'm not set on the structure, if you think something else makes more sense, go ahead :D

[kylefhartzenberg]

That makes sense. I thought the same but I didn't want to interfere with the existing structure. The requested changes have been made. Let me know if you'd like anything else updated/edited.

[L3MON4D3]

Good instinct :D
I'm happy with the content, could you move the section between Config-Options and Api?
And then squash all commits into just one?

[kylefhartzenberg]

Done and done. Also, added a link at the bottom of the original Snippet-specific filetypes section to reference relevant sub-section that's now in Troubleshooting.

[L3MON4D3]

Beautiful, thank you very much!