[docs] Contributing first PR (#4159)

* [docs] Contributing first PR

Based on https://github.com/open-telemetry/opentelemetry-go/blob/3ec70fd0379970acf00959c14a72885b984a7b09/CONTRIBUTING.md#how-to-receive-comments

* Update docs/CONTRIBUTING.md

Co-authored-by: Chris Ventura <[email protected]>

---------

Co-authored-by: Chris Ventura <[email protected]>

Author: Kielek

docs/CONTRIBUTING.md

@@ -60,3 +60,92 @@ on something that maintainers may decide this repo is not the right place for.
 
 See [developing.md](developing.md) to learn more about
 the development environment setup and usage.
+
+## Create Your First Pull Request
+
+### How to Send Pull Requests
+
+Everyone is welcome to contribute code to `opentelemetry-dotnet-instrumentation`
+via GitHub pull requests (PRs).
+
+To create a new PR, fork the project in GitHub and clone the upstream repo:
+
+> [!NOTE]
+> Please fork to a personal GitHub account rather than a corporate/enterprise
+> one so maintainers can push commits to your branch.
+> **Pull requests from protected forks will not be accepted.**
+
+```sh
+git clone https://github.com/open-telemetry/opentelemetry-dotnet-instrumentation.git
+```
+
+Navigate to the repo root:
+
+```sh
+cd opentelemetry-dotnet-instrumentation
+```
+
+Add your fork as an origin:
+
+```sh
+git remote add fork https://github.com/YOUR_GITHUB_USERNAME/opentelemetry-dotnet-instrumentation.git
+```
+
+Check out a new branch, make modifications and push the branch to your fork:
+
+```sh
+$ git checkout -b feature
+# change files
+# Test your changes locally.
+$ nuke Workflow
+$ git add my/changed/files
+$ git commit -m "short description of the change"
+$ git push fork feature
+```
+
+Open a pull request against the main `opentelemetry-demo` repo.
+
+### How to Receive Comments
+
+* If the PR is not ready for review, please mark it as
+  [`draft`](https://github.blog/2019-02-14-introducing-draft-pull-requests/).
+* Make sure CLA is signed and all required CI checks are clear.
+* Submit small, focused PRs addressing a single
+  concern/issue.
+* Make sure the PR title reflects the contribution.
+* Write a summary that helps understand the change.
+* Include usage examples in the summary, where applicable.
+* Include benchmarks (before/after) in the summary, for contributions that are
+  performance enhancements.
+
+### How to Get PRs Merged
+
+A PR is considered to be **ready to merge** when:
+
+* It has received approval from
+  [Approvers](https://github.com/open-telemetry/community/blob/main/guides/contributor/membership.md#approver)
+  /
+  [Maintainers](https://github.com/open-telemetry/community/blob/main/guides/contributor/membership.md#maintainer).
+* Major feedbacks are resolved.
+* The documentation and [Changelog](../CHANGELOG.md) have been updated
+  to reflect the new changes.
+
+Any Maintainer can merge the PR once it is **ready to merge**. Note, that some
+PRs may not be merged immediately if the repo is in the process of a release and
+the maintainers decided to defer the PR to the next release train.
+
+If a PR has been stuck (e.g. there are lots of debates and people couldn't agree
+on each other), the owner should try to get people aligned by:
+
+* Consolidating the perspectives and putting a summary in the PR. It is
+  recommended to add a link into the PR description, which points to a comment
+  with a summary in the PR conversation.
+* Tagging subdomain experts (by looking at the change history) in the PR asking
+  for suggestion.
+* Reaching out to more people on the [CNCF OpenTelemetry Automatic
+  instrumentation for .NET Slack channel](https://cloud-native.slack.com/archives/C01NR1YLSE7).
+* Stepping back to see if it makes sense to narrow down the scope of the PR or
+  split it up.
+* If none of the above worked and the PR has been stuck for more than 2 weeks,
+  the owner should bring it to the OpenTelemetry Automatic Instrumentation SIG
+  [meeting](README.md#contributing).