Tutorial links to line-numbers are out of date

[scpeters]

Some links to lines of code in a tutorial are out of date (see https://github.com/ignitionrobotics/ign-physics/pull/191/files#r557676961). They are pointing to branches rather than specific commits, and the line numbers are no longer accurate.

Also, there is a reference to master in that same paragraph that should be updated to main.

[Ambuj-Pandey]

i am new to open source and want to contribute also want to work on this my very first issue . Can you please guide me ??

[ahcorde]

Hi @Ambuj-Pandey,

My recommendations:

• read this document about how to contibute to Ignition Robotics
• learn how to contribute to an Open Source Project.

Then select an issue (like this one, tagged as "good first issue") and start contributing!