docs: fix missing punctuation

Signed-off-by: Athan <[email protected]>

Author: kgryte

lib/node_modules/@stdlib/stats/base/mean/README.md

@@ -106,7 +106,7 @@ The function has the following additional parameters:
 
 -   **offsetX**: starting index for `x`.
 
-While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying buffer, the offset parameter supports indexing semantics based on a starting index For example, to calculate the [arithmetic mean][arithmetic-mean] for every other element in `x` starting from the second element
+While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying buffer, the offset parameter supports indexing semantics based on a starting index. For example, to calculate the [arithmetic mean][arithmetic-mean] for every other element in `x` starting from the second element
 
 ```javascript
 var x = [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ];