minor fix for security doc

[konabuta]

Purpose

• minor fix for spelling, space etc.

Does this introduce a breaking change?

[ ] Yes
[x] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[x] Documentation content changes
[ ] Other... Please describe:

How to Test

• Get the code
  n/a

git clone [repo-address]
cd [repo-name]
git checkout [branch-name]
npm install

• Test the code
  n/a

What to Check

Verify that the following are valid

• n/a

Other Information

[konabuta]

@kotetz Do you plan to add Recover section?