Minor changes in wording/spelling and added more Doc Strings

Minor changes in wording/spelling in README: Added more Doc Strings to cli.py; minor correction of spelling in Doc Strings in main.py

tsg/main.py

@@ -11,7 +11,7 @@ LOG = logging.getLogger(__name__)
 
 
 def read_abundances(transcripts_file: str) -> pd.DataFrame:
-    """Read file of abundance of transcripts into dataframe.
+    """Read transcript-abundance file into dataframe.
 
     Args:
         transcripts_file (str): Input filename
@@ -32,7 +32,7 @@ def read_abundances(transcripts_file: str) -> pd.DataFrame:
 
 
 def filter_df(df: pd.DataFrame, transcripts: list = []) -> pd.DataFrame:
-    """Filter annotations to include only exons with the highest transcript support level, i.e. (TSL1).
+    """Filter annotations to include only exons with the highest transcript support level, i.e. TSL1.
 
     `feature` column is filtered on value "exon" and
     `free_text` column is filtered to include the string denoting the highest transcript support level