tiny grammar change: remove use of word 'so' (#1681)

The sentence I edited begins with 'since'.
Because it begins with 'since', the second clause
of the sentence is a conclusion. 'so' indicates
a conclusion follows. The sentence I edited used both
'since' and 'so', but 'since' is enough to indicate
a conclusion follows, so I remove 'so'.

Co-authored-by: Diego Molina <[email protected]>

Author: zipperer

website_and_docs/content/documentation/webdriver/waits.en.md

@@ -92,7 +92,7 @@ _Explicit waits_ are loops added to the code that poll the application
 for a specific condition to evaluate as true before it exits the loop and
 continues to the next command in the code. If the condition is not met before a designated timeout value, 
 the code will give a timeout error. Since there are many ways for the application not to be in the desired state,
-so explicit waits are a great choice to specify the exact condition to wait for
+explicit waits are a great choice to specify the exact condition to wait for
 in each place it is needed. 
 Another nice feature is that, by default, the Selenium Wait class automatically waits for the designated element to exist.