Merge pull request #194 from NOAA-GFDL/update-yamltools-readme

Update yamltools README.md

fre/yamltools/README.md

@@ -1,6 +1,17 @@
 ## FRE yamltools
-### Tools:
-- `combine-yaml.py`: creates a `combined-[experiment name].yaml` file in which the [model].yaml, compile.yaml, platforms.yaml, [experiment].yaml, and [analysisscript].yaml are merged
+`fre yamltools` provides subtools that help to manage and perform operations on yaml files. 
+
+## Subtools
+- `fre yamltools combine-yamls [options]`
+   - Purpose: 
+        - Creates combined yaml file in which the [model].yaml, compile.yaml, and platforms.yaml are merged if `--use compile` is specified
+        - Creates combined yaml file in which the [model].yaml, [experiment].yaml, and [analysis].yaml are merged if `--use pp` is specified
+   - Options:
+        - `-y, --yamlfile [experiment yaml] (required)`
+        - `-p, --platform [platform] (required)`
+        - `-t, --target [target] (required)`
+        - `-e,  --experiment [experiment name]`
+        - `--use [compile|pp] (required)`
 
 ### **Tests**