small doc/readme fixes (#921)

Signed-off-by: Hugo KULESZA <hugo.kulesza@rte-france.com>

README.md

@@ -100,7 +100,7 @@ Requirements:
 To build from sources and install PyPowSyBl package:
 
 ```bash
-git clone --recursive https://github.com/powsybl/pypowsybl.git
+git clone https://github.com/powsybl/pypowsybl.git
 export JAVA_HOME=<path to GraalVM>
 pip install --upgrade setuptools pip
 pip install -r requirements.txt

pypowsybl/network/impl/network.py

@@ -3732,7 +3732,7 @@ def create_extensions(self, extension_name: str, df: Union[DataFrame, List[Optio
 
         Args:
             extension_name: name of the extension
-            dfs: the data to be created
+            df: the data to be created
                  A single dataframe or a list of dataframes can be given as arguments
             kwargs: the data to be created, as named arguments.
                     Arguments can be single values or any type of sequence.
@@ -3842,7 +3842,7 @@ def get_operational_limits(self, all_attributes: bool = False, attributes: List[
             all_attributes: flag for including all attributes in the dataframe, default is false
             attributes:     attributes to include in the dataframe. The 2 parameters are mutually
                             exclusive. If no parameter is specified, the dataframe will include the default attributes.
-            only_selected_sets: flag to choose whether inactive limit sets should also be included in the dataframe
+            show_inactive_sets: flag to choose whether inactive limit sets should also be included in the dataframe
 
         Returns:
             All limits on the network