hotfix: Update architecture-and-requirements.md

[adrach]

What is this PR for?

simple typo fix in the docs

What type of PR is it?

Bug Fix

How should this be tested?

Just hop into the /docs/designDocs/architecture-and-requirements and check the page title

Screenshots (if appropriate)

Questions:

• Do the license files need updating? No
• Are there breaking changes for older versions? No
• Does this need new documentation? No

[cdmikechen]

@adrach
Hi~ Thanks for your pull request.
We need a corresponding jira issue (https://issues.apache.org/jira/projects/SUBMARINE/issues) for each of our PRs.
If it's convenient for you, could you first create a jira issue and change the title like any other PR and put the issue link inside the description of the PR?

[codecov]

Codecov Report

Merging #1084 (c71699e) into master (f7c2fe5) will not change coverage.
Report is 8 commits behind head on master.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1084   +/-   ##
=======================================
  Coverage   67.27%   67.27%           
=======================================
  Files         128      128           
  Lines        6224     6224           
=======================================
  Hits         4187     4187           
  Misses       2037     2037           

Flag	Coverage Δ
python-integration	54.20% <ø> (ø)
python-unit	48.00% <ø> (ø)

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