Add back the 2->3 upgrade docs

[Joseph2001-braganza]

Kindly Check the Documentation which I have updated for updating Mautic 2.x to 3.x.
If this is fine then I can move forward and add the documentation for 3.x to 4.x !
Thanks

Fixes #222

[jos0405]

1. Plz remove the part where you name the plugins you are cleaning up
2. Please remove the DB password
3. Please change the sudo commands as they are not working like this in every environment
4. Plz rewrite the code to work relatively and don't hardcore all your path

[Joseph2001-braganza]

Ok got it will work on this

[RCheesley]

Hi @Joseph2001-braganza are you still OK to make the tweaks requested from @jos0405 ?

[Joseph2001-braganza]

Hi @Joseph2001-braganza are you still OK to make the tweaks requested from @jos0405 ?

yes working on it.

[Joseph2001-braganza]

Hi @Joseph2001-braganza are you still OK to make the tweaks requested from @jos0405 ?

yes working on it.

@jos0405 and @RCheesley Could you review my updated PR
Thanks

[RCheesley]

@Joseph2001-braganza please can you take a look at the Vale issues which are reported? Let us know if you need help with fixing them.

[Joseph2001-braganza]

@Joseph2001-braganza please can you take a look at the Vale issues which are reported? Let us know if you need help with fixing them.

sure will look into this .

[Joseph2001-braganza]

@Joseph2001-braganza please can you take a look at the Vale issues which are reported? Let us know if you need help with fixing them.

sure will look into this .

Hi @RCheesley , I have made the changes accordingly suggested by Vale, but it was showing me errors in some other files like readme.md and install Mautic page. I have only changed the "how to update the Mautic" or should I rectify those errors also ?

[RCheesley]

There's still a lot of feedback that needs fixing @Joseph2001-braganza - just on this file. Check the files changed tab and it will show you what needs changing.

[Joseph2001-braganza]

There's still a lot of feedback that needs fixing @Joseph2001-braganza - just on this file. Check the files changed tab and it will show you what needs changing.

Ok I will try to fix it .

[RCheesley]

Hi @Joseph2001-braganza do you feel you can continue with this and address the feedback?