Update the comment for NewEnterpriseClient

[suhaibmujahid]

In the pull request #1178, the behavior on the client instantiation change to use a new http.Client instead of using the http.DefaultClient. This change is reflected in the comment block for NewClient but not for NewEnterpriseClient .

[codecov]

Codecov Report

Merging #1464 into master will not change coverage by %.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1464   +/-   ##
=======================================
  Coverage   68.16%   68.16%           
=======================================
  Files          94       94           
  Lines        8419     8419           
=======================================
  Hits         5739     5739           
  Misses       1819     1819           
  Partials      861      861           

Impacted Files	Coverage Δ
github/github.go	89.77% <ø> (ø)

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[gmlewis]

Thank you, @suhaibmujahid!
LGTM.
Merging.