docs: update golang version in Dockerfile to correct 1.10.4

[allencloud]

Signed-off-by: Allen Sun [email protected]

Ⅰ. Describe what this PR did

In pr #2321 we have upgrade golang version into 1.10.4, while the goversion in Dockerfile is still 1.9.1.

This pr updates golang version in Dockerfile to correct 1.10.4

Ⅱ. Does this pull request fix one issue?

none

Ⅲ. Why don't you add test cases (unit test/integration test)? (你真的觉得不需要加测试吗？)

no need, only doc update.

Ⅳ. Describe how to verify it

none

Ⅴ. Special notes for reviews

none

[codecov]

Codecov Report

Merging #2419 into master will increase coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2419      +/-   ##
==========================================
+ Coverage   68.44%   68.48%   +0.04%     
==========================================
  Files         275      275              
  Lines       18309    18309              
==========================================
+ Hits        12531    12539       +8     
+ Misses       4349     4344       -5     
+ Partials     1429     1426       -3

Flag	Coverage Δ
#criv1alpha1test	31.68% <ø> (-0.13%)	⬇️
#criv1alpha2test	35.76% <ø> (-0.07%)	⬇️
#integrationtest	39.85% <ø> (+0.01%)	⬆️
#nodee2etest	33.25% <ø> (+0.15%)	⬆️
#unittest	25.49% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
daemon/mgr/system.go	67.93% <0%> (-5.35%)	⬇️
ctrd/watch.go	80.3% <0%> (-3.04%)	⬇️
cri/v1alpha2/cri_wrapper.go	61.2% <0%> (-2.4%)	⬇️
daemon/containerio/container_io.go	74.86% <0%> (-1.1%)	⬇️
cri/v1alpha2/cri.go	68.05% <0%> (+0.23%)	⬆️
cri/v1alpha1/cri.go	61.03% <0%> (+0.32%)	⬆️
daemon/mgr/container.go	60.66% <0%> (+0.42%)	⬆️
cri/v1alpha2/cri_utils.go	91.09% <0%> (+0.57%)	⬆️
ctrd/client.go	69.23% <0%> (+2.3%)	⬆️
daemon/mgr/events.go	100% <0%> (+3.7%)	⬆️
... and 2 more

[fuweid]

LGTM