add a readme file for parameters mapping workflow

Author: evacougnon

PARAMETERS_MAPPING/README.parameters-mapping.md

@@ -0,0 +1,40 @@
+# Parameters Mapping or how to add a metadata header for CSV files
+
+1. check that the parameters to add are listed in [data-services](https://github.com/aodn/data-services/tree/master/PARAMETERS_MAPPING)
+    * ```parameters.csv``` list of available parameters and their ids
+    * ```qc_flags.csv```
+    * ```qc_scheme.csv```
+    * ```unit_view.csv``` list the available units and their ids (cf names, longnames and id)
+
+1. New parameters
+    * needs to follow the IMOS vocabulary [BENE PLEASE UPDATE]
+
+1. map the parameters for your dataset collection
+    * update ```parameters_mapping.csv```. This is the file where all the information from the other files is brought together, and where a variable name as written in the column name of the csv is matched to a unique id for each parameters find in ```parameters.csv```, units find in ```unit_view.csv```, ...
+
+1. Create view in Parameters mapping harvester: update the liquibase to update/include new views in the [harvester](https://github.com/aodn/harvesters/tree/master/workspace/PARAMETERS_MAPPING)
+    * start your stack restoring the paramaters_mapping schema and the schema you are working on
+    ```RestoreDatabaseSchemas: - schema: parameters_mapping, - schema: working_schema```
+    * open pgadmin and access your stack-db to test the sql query that will be used to create/update the view in the parameters_mapping harvester, as it is easier to get a better understanding of the query before updating the liquibase via Talend
+    * start  your pipeline box and Talend 
+    * update liquidbase in the second components ```Create parameters_mapping views``` 
+        * the query will crash because of 6 views are calling their respective dataset collection schema: 
+    `aatams_biologging_shearwater_metadata_summary`; 
+    `aatams_biologging_snowpetrel_metadata_summary`; 
+    `aatams_sattag_dm_metadata_summary`; 
+    `aatams_sattag_nrt_metadata_summary`; 
+    `aodn_nt_sattag_hawksbill_metadata_summary`; 
+    `aodn_nt_sattag_oliveridley_metadata_summary`
+    * write the new view you are working on at the top of the liquidbase script, so Talend can run and create before crashing at `aatams_biologging_shearwater_metadata_summary` 
+    * check stack database that the views are created as expected
+
+1. merge the changes made in
+    * [data-services](https://github.com/aodn/data-services/tree/master/PARAMETERS_MAPPING) 
+    * [harvester](https://github.com/aodn/harvesters/tree/master/workspace/PARAMETERS_MAPPING) to test on RC before merging to production
+
+1. test on RC, check the csv files a user can download from the portal
+
+# Other information
+The [PARAMETERS_MAPPING harvester](https://github.com/aodn/harvesters/tree/master/workspace/PARAMETERS_MAPPING) runs on a cron job daily , Monday to Friday.
+It harvests the content of these 5 files into the parameters_mapping DB schema and create a _metadata_summary view for each of the collection listed (it is not IMOS specific, for example we have a mapping for the AODN _WAVE_DM + NRT collections)
+