[Doc] Update getting_started.rst

[koug44]

Replacing command to install Sanic without uvloop as the provided one is not working (at least in my case)

I've took the working from your Pypi page

[codecov]

Codecov Report

Merging #1814 into master will increase coverage by 0.23%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1814      +/-   ##
==========================================
+ Coverage   91.94%   92.18%   +0.23%     
==========================================
  Files          23       23              
  Lines        2309     2315       +6     
  Branches      428      425       -3     
==========================================
+ Hits         2123     2134      +11     
+ Misses        143      141       -2     
+ Partials       43       40       -3     

Impacted Files	Coverage Δ
sanic/response.py	98.06% <0.00%> (-0.63%)	⬇️
sanic/views.py	100.00% <0.00%> (ø)
sanic/request.py	99.62% <0.00%> (+<0.01%)	⬆️
sanic/testing.py	97.97% <0.00%> (+0.02%)	⬆️
sanic/app.py	92.25% <0.00%> (+0.41%)	⬆️
sanic/router.py	97.07% <0.00%> (+1.51%)	⬆️
sanic/compat.py	86.20% <0.00%> (+16.97%)	⬆️

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[yunstanford]

hmm.. it's still waiting for travis-ci to report back results, looks like hanging there forever. Maybe it's easy to just bring up another pr

[Tronic]

There were hangs like this with Travis on other PRs too, about two weeks ago. Making any new change on this will re-run it, probably with success. Most current PRs display various test failures although in reality they are all-OK, because of this and other test problems that should now be all fixed.

This PR in particular only affects docs in a way that could hardly cause any test failures.

[yunstanford]

Yeah, but the merge button is disabled, and i can't merge it until travis-ci reports results back

[Tronic]

@koug44 Could you push something (like merge master) to this PR so that tests can be run again and this can be merged? sigh

[koug44]

@koug44 Could you push something (like merge master) to this PR so that tests can be run again and this can be merged? sigh
Done