bugfix: Add missing document in Makefile

[chuanchang]

Add missing document and unify upper and lower case letters.

Signed-off-by: Alex Jia [email protected]

Ⅰ. Describe what this PR did

Add missing document and unify upper and lower case letters.

Ⅱ. Does this pull request fix one issue?

Nothing

Ⅲ. Describe how you did it

Ⅳ. Describe how to verify it

make help

Ⅴ. Special notes for reviews

[codecov-io]

Codecov Report

Merging #1757 into master will increase coverage by 0.1%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master    #1757     +/-   ##
=========================================
+ Coverage   56.26%   56.37%   +0.1%     
=========================================
  Files         200      200             
  Lines       15657    15657             
=========================================
+ Hits         8809     8826     +17     
+ Misses       5755     5738     -17     
  Partials     1093     1093

Flag	Coverage Δ
#critest	33.55% <ø> (+0.01%)	⬆️
#integrationtest	37.67% <ø> (+0.21%)	⬆️
#unittest	20.33% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
cri/stream/httpstream/spdy/upgrade.go	54.28% <0%> (-5.72%)	⬇️
ctrd/container.go	49.48% <0%> (-0.69%)	⬇️
cri/v1alpha2/cri.go	65.96% <0%> (-0.18%)	⬇️
daemon/mgr/container.go	53.3% <0%> (-0.16%)	⬇️
daemon/mgr/system.go	75% <0%> (+1.72%)	⬆️
daemon/mgr/container_utils.go	58% <0%> (+1.73%)	⬆️
ctrd/image.go	78.71% <0%> (+1.98%)	⬆️
daemon/containerio/container_io.go	75.69% <0%> (+2.2%)	⬆️
ctrd/watch.go	78.12% <0%> (+3.12%)	⬆️
apis/server/utils.go	66.66% <0%> (+4.76%)	⬆️
... and 1 more