Correct base template name

The base template name used in $loader1 and $loader2 is actually
"base.html", not "base.twig".
minor #1546 [doc] [api.rst] Correct base template name (fabschurt)

This PR was merged into the 1.16-dev branch.

Discussion
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[doc] [api.rst] Correct base template name

The base template name used in $loader1 and $loader2 is actually "base.html", not "base.twig".

Commits
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882f44b Correct base template name