add CLI readme + add to root readme (#48)

* add CLI readme + add to root readme

* fix typo

Author: bartveneman

README.md

@@ -87,3 +87,13 @@ for (let file of files) {
 	coverage_data.push(...parse_coverage(json_content))
 }
 ```
+
+## CLI
+
+Use the CLI tool (`css-coverage`) to check if coverage meets minimum requirements, globally and/or per file.
+
+```sh
+css-coverage --coverage-dir=<dir> --min-coverage=<number> [options]
+```
+
+[CLI docs](src/cli/README.md)

src/cli/README.md

@@ -0,0 +1,35 @@
+# CSS Code Coverage CLI
+
+```
+USAGE
+  $ css-coverage --coverage-dir=<dir> --min-coverage=<number> [options]
+
+OPTIONS
+Required:
+  --coverage-dir        Where your Coverage JSON files are
+  --min-coverage        Minimum overall CSS coverage [0-1]
+
+Optional:
+  --min-file-coverage   Minimal coverage per file [0-1]
+
+  --show-uncovered      Which files to show when not meeting
+                        the --min-file-line-coverage threshold
+                        • violations [default] show under-threshold files
+                        • all show partially covered files
+                        • none do not show files
+
+  --reporter            How to show the results
+                        • pretty [default]
+                        • tap
+                        • json
+
+EXAMPLES
+  # analyze all .json files in ./coverage; require 80% overall coverage
+  $ css-coverage --coverage-dir=./coverage --min-coverage=0.8
+
+  # Require 50% coverage per file
+  $ css-coverage --coverage-dir=./coverage --min-coverage=0.8 --min-file-coverage=0.5
+
+  Report JSON
+  $ css-coverage --coverage-dir=./coverage --min-coverage=0.8 --reporter=json
+```