docs: clarify supported deployment strategies

[johnmwood]

The current concept docs seem to suggest that Recreate and RollingUpdate deployment strategies are supported by Argo Rollouts:

To make it clear how the Argo Rollouts will behave, here are the descriptions of the various deployment strategies implementations offered by the Argo Rollouts.

I changed the wording in this PR to make the supported APIs more clear. This line caused some confusion on our end because we believed that users had the option to use Recreate or RollingUpdate strategies and we wanted to reject any Rollout admissions with those strategies.

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this is a chore.
• The title of the PR is (a) conventional with a list of types and scopes found here, (b) states what changed, and (c) suffixes the related issues number. E.g. "fix(controller): Updates such and such. Fixes #1234".
• I've signed my commits with DCO
• I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
• My builds are green. Try syncing with master if they are not.
• My organization is added to USERS.md.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[github-actions]

Published E2E Test Results

  4 files    4 suites   3h 14m 34s ⏱️
113 tests 103 ✅  7 💤 3 ❌
456 runs  425 ✅ 28 💤 3 ❌

For more details on these failures, see this check.

Results for commit 1024744.

[github-actions]

Published Unit Test Results

2 275 tests   2 275 ✅  2m 58s ⏱️
  128 suites      0 💤
    1 files        0 ❌

Results for commit 1024744.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.89%. Comparing base (bfef7f0) to head (1024744).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3823      +/-   ##
==========================================
+ Coverage   83.86%   83.89%   +0.03%     
==========================================
  Files         163      163              
  Lines       18560    18560              
==========================================
+ Hits        15565    15571       +6     
+ Misses       2121     2118       -3     
+ Partials      874      871       -3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.