Update README.md

[SharathRajMohan]

Fixed command to install python packages. Added the -r flag to the command pip install requirements.txt

What changes are proposed in this pull request?

• Corrected the dependency installation command in the quick install section.

(Please fill in changes proposed in this fix)

How is this patch tested?

• Documentation Update.
  (Details)

We require adding a link to the workflow for testing the mlflow/recipes-regression-template code path.

Run the workflow with repository name: mlflow/recipes-regression-template and the branch(Example:<user-name>:feature) that you are working with.

Release Notes

Is this a user-facing change?

• No. You can skip the rest of this section.
• Yes. Give a description of this change to be included in the release notes for MLflow users.

(Details in 1-2 sentences. You can just refer to another PR with a description if this PR is part of a larger change.)

What component(s), interfaces, languages, and integrations does this PR affect?

Components

• area/regression: Sklearn regression recipe example
• area/build: Build and test infrastructure for MLflow recipe example

How should the PR be classified in the release notes? Choose one:

• rn/breaking-change - The PR will be mentioned in the "Breaking Changes" section
• rn/none - No description will be included. The PR will be mentioned only by the PR number in the "Small Bugfixes and Documentation Updates" section
• rn/feature - A new user-facing feature worth mentioning in the release notes
• rn/bug-fix - A user-facing bug fix worth mentioning in the release notes
• rn/documentation - A user-facing documentation change worth mentioning in the release notes