Add documentation for NightlyTestManual

Author: AmirhosseinPoolad

README.developers.md

@@ -301,6 +301,18 @@ For the very large runs, you can submit your runs on a large cluster. A template
 a Slurm-managed cluster can be found under vtr_flow/tasks/slurm/
 
 ## Continuous integration (CI)
+
+### Manual Nightly Tests
+
+You can use remote servers to run the [vtr_reg_nightly_test1-7](#vtr_reg_nightly_test1-N) tests. These tests are triggered manually by going to the GitHub Actions menu, selecting the NightlyTestManual workflow and selecting run workflow. Once you do that, the [Nightly Test Manual Workflow](https://github.com/verilog-to-routing/vtr-verilog-to-routing/blob/master/.github/workflows/nightly_test_manual.yml) will be triggered. This run will take approximately 15 hours to complete and will cancel any currently running workflows.
+
+<img src="https://raw.githubusercontent.com/verilog-to-routing/vtr-verilog-to-routing/master/doc/src/dev/run_ci_manual/select_actions.png" alt="Select GitHub Actions menu" width="60%"/>
+<br/>
+<img src="https://raw.githubusercontent.com/verilog-to-routing/vtr-verilog-to-routing/master/doc/src/dev/run_ci_manual/select_workflow.png" alt="Select the NightlyTestManual workflow" width="30%"/>
+<img src="https://raw.githubusercontent.com/verilog-to-routing/vtr-verilog-to-routing/master/doc/src/dev/run_ci_manual/run_workflow.png" alt="Run the Workflow" width="30%"/>
+
+### Other CI Tests
+
 For the following tests, you can use remote servers instead of running them locally. Once the changes are pushed into the 
 remote repository, or a PR is created, the [Test Workflow](https://github.com/verilog-to-routing/vtr-verilog-to-routing/blob/master/.github/workflows/test.yml)
 will be triggered. Many tests are included in the workflow, including: