Update src/bm25_transformer.jl - spacing

Co-authored-by: Jose Storopoli <[email protected]>

Author: pazzo83

src/bm25_transformer.jl

@@ -11,7 +11,7 @@ the probability that a user will consider a search result relevant based on the
 and those in each document.
 
 The parameters `max_doc_freq`, `min_doc_freq`, and `smooth_idf` all work identically to those in the
-`TfidfTransformer`.  BM25 introduces two additional parameters:
+`TfidfTransformer`. BM25 introduces two additional parameters:
 
 `κ` is the term frequency saturation characteristic.  Higher values represent slower saturation.  What 
 we mean by saturation is the degree to which a term occuring extra times adds to the overall score.  This defaults