typo in doc for "Miscellaneous Coding Conventions"

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/13/source-conventions.html
Description:

small fix in description at [1] as follows

-If that were not done interrupted code that's currently inspecting errno
might see the wrong value.
+If that was not done interrupted code that's currently inspecting errno
might see the wrong value.

[1]https://www.postgresql.org/docs/devel/source-conventions.html