ncu-ci: add docs

Author: joyeecheung

docs/ncu-ci.md

@@ -0,0 +1,41 @@
+# ncu-ci
+
+Parse the results of a Jenkins CI run in https://ci.nodejs.org/ and display
+a summary for all the failures.
+
+Supported jobs:
+
+- [node-test-pull-request](https://ci.nodejs.org/job/node-test-pull-request)
+- [node-test-commit](https://ci.nodejs.org/job/node-test-commit)
+- [benchmark-node-micro-benchmarks](https://ci.nodejs.org/job/benchmark-node-micro-benchmarks/)
+
+```
+ncu-ci <command>
+
+Commands:
+  ncu-ci url <url>          Automatically detect CI type and show results
+  ncu-ci pr <jobid>         Show results of a node-test-pull-request CI job
+  ncu-ci commit <jobid>     Show results of a node-test-commit CI job
+  ncu-ci benchmark <jobid>  Show results of a benchmark-node-micro-benchmarks CI
+                            job
+
+Options:
+  --version  Show version number                                       [boolean]
+  --copy     Write the results as markdown to clipboard         [default: false]
+  --help     Show help                                                 [boolean]
+```
+
+## Example
+
+Get the CI results of PR 12345 (including latest results of each type of
+supported CI) and copy the summaries into clipboard:
+
+```
+ncu-ci url https://github.com/nodejs/node/pull/12345 --copy
+```
+
+Get the results of job #12345 of  `node-test-pull-request`:
+
+```
+ncu-ci pr 12345
+```