Update PCA.md

Co-authored-by: Gregor Gorjanc <gregor.gorjanc@gmail.com>

Author: hannesbecher

PCA.md

@@ -208,7 +208,7 @@ Above we showed how variant and branch-based PCA are equivalent. But the ARG is
 pctime=[tsm.pca(num_components=10, time_windows=[10**i, 10**(i+1)]) for i in range(8)]
 ```
 
-Being of class `PCAResult`, the elements of the list have a `factors` property. This has a shape of (100,10). I.e., 10 PCs for 100 haplotypes.
+Being of class `PCAResult`, the elements of the list have a `factors` property. This has a shape of `(100,10)`, that is, 10 PCs for 100 haplotypes.
 
 ```{code-cell} ipython3
 pctime[0].factors.shape