fix: make Installation more compatible

[allencloud]

Signed-off-by: Allen Sun allensun.shl@alibaba-inc.com

Ⅰ. Describe what this PR did

I am using a VM on QingCloud to install Pouch. I found that when I copy the installation command to terminal of VM, it will paste some unexpected char, see:

root@i-qvufr3ii:~# sudo apt-get install \
> .apt-transport-https \
> .ca-certificates \
> .curl \
> .software-properties-common

In fact, . is out of expect.

So I update the installation.md to fix this to avoid unexpected behavior.

Ⅱ. Does this pull request fix one issue?

no

Ⅲ. Describe how you did it

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov-io]

Codecov Report

Merging #930 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #930   +/-   ##
=======================================
  Coverage   13.32%   13.32%           
=======================================
  Files         122      122           
  Lines        7872     7872           
=======================================
  Hits         1049     1049           
  Misses       6732     6732           
  Partials       91       91

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[allencloud]

LGTM