newcomers_guide.rst: add a warning for not to use git pull CLI command

[shikharvaish28]

In the newcomer's docs, there needs to be warning for not using the git pull command in CLI as it can cause conflicts in the PR.

This can be a good newcomer issue.

[li-boxuan]

There is no git pull button :P Instead, people should not use git pull command on CLI.

[shikharvaish28]

My bad. Fixed.

[shriram98]

I would like to be assigned this issue as my newcomer task

[jayvdb]

@shriram98 , this one is reserved for Google Code-in . Please find another one on https://coala.io/new

[jayvdb]

This issue reserved for Google Code-in task 5682493584834560.

[ghost]

So Google Code-in is assigned this issue. But Assignees tab on top-right shows:

No one assigned

It's just confusing. Thus time consuming/wasting. Could there be a clearer placeholder or a label? To help other newcomers.

[ghost]

Could there be a clearer placeholder or a label?

Saw a thread explaining what initiatives/gci means. It means task is assigned to Google Code-In and thus not available to newcomers. Thanks.

This is still confusing for those who don't know the meaning of the label.

[criticic]

@jayvdb @li-boxuan As GCI is over , Please assign this issue to me

[Dilshaad21]

Can I take up this issue.

[KVGarg]

@Dilshaad21 You've already worked on a newcomer issue. Please follow the newcomers guide! and look for a low difficulty issue. Thnx 👍

[MrUnfunny]

I would like to be assigned to this issue as it is still unassigned.

[piyushpalawat99]

@abhishalya Can I work on this issue?

[abhishalya]

@piyushpalawat99 Invited you, accept and ping again.

[piyushpalawat99]

@abhishalya accepted