Update readme (#127)

* add extra and simple transform to readme

* formatting

* titles

README.md

@@ -19,6 +19,13 @@ ODS_Tools can be installed via pip by running the following command:
 pip install ods-tools
 ```
 
+If using the `transform` command, use instead 
+
+```
+pip install ods-tools[extra]
+```
+
+which will install some optional packages needed for it.
 
 ## command line interface
 
@@ -241,8 +248,22 @@ oed_exposure.reporting_currency = 'EUR' # this line will trigger currency conver
 ### Format Conversions
 
 The `transform` command can be used to convert between OED and other formats.
+To run transformations, and extra set of packages must be installed. This can be done using `pip install ods-tools[extra]` (or `pip install --upgrade ods-tools[extra]` if already installed).
 
-`ods_tools transform` requires a configuration file, passed with the option `--config-file`. It must contain:
+**Basic csv conversion**
+
+A simple csv-to-csv transformation can be run from the command line with 
+```
+ods_tools transform -f air-oed --input-file source.csv --output-file output.csv
+```
+
+The flag -f instructs the tool on which are the origin and destination formats (currently air and oed).
+
+**Complex conversions**
+
+More complex transformations run with `ods_tools transform` requires a configuration file, passed with the option `--config-file`. Please see the docs [here](https://oasislmf.github.io/sections/ODTF.html)
+
+A configuration file must contain:
 
 - type of file to transform (location or account)
 - input format
@@ -275,7 +296,7 @@ transformations:
 ```
 
 
-In order for a transformation to be run, the folder `./ods_tools/odtf/data/mappings` must contain the appropriate yaml configuration file that describes the transformations to perform on the input file to obtain the output (and, potentially, vice versa). Currently, only [mapping_loc_Cede-OED.yaml](./ods_tools/odtf/data/mappings/mapping_loc_Cede-OED.yaml) and
+For a transformation to be run, the folder `./ods_tools/odtf/data/mappings` must contain the appropriate yaml configuration file that describes the transformations to perform on the input file to obtain the output (and, potentially, vice versa). Currently, only [mapping_loc_Cede-OED.yaml](./ods_tools/odtf/data/mappings/mapping_loc_Cede-OED.yaml) and
 [mapping_acc_Cede-OED.yaml](./ods_tools/odtf/data/mappings/mapping_acc_Cede-OED.yaml) are provided; they describe the transformation between AIR Cede v10.0.0 and OED 3.0.2 for location and account files respectively.
 
 The transformation can be run using:
@@ -284,9 +305,10 @@ The transformation can be run using:
 ods_tools transform --config-file configuration.yaml
 ```
 
+**Options**
+
 The following options can be used to adjust the process:
 
 `--nocheck` to skip the oed validation at the end of the conversion
 
 `-v` to adjust the logging level (debug:10, info:20, warning:30, error:40, critical:50)
-