docs: add missing webview render-process-gone event (#39545)

docs: add mising webview 'render-process-gone' event

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Milan Burda <milan.burda@gmail.com>

docs/api/structures/render-process-gone-details.md

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+# RenderProcessGoneDetails Object
+
+* `reason` string - The reason the render process is gone.  Possible values:
+  * `clean-exit` - Process exited with an exit code of zero
+  * `abnormal-exit` - Process exited with a non-zero exit code
+  * `killed` - Process was sent a SIGTERM or otherwise killed externally
+  * `crashed` - Process crashed
+  * `oom` - Process ran out of memory
+  * `launch-failed` - Process never successfully launched
+  * `integrity-failure` - Windows code integrity checks failed
+* `exitCode` Integer - The exit code of the process, unless `reason` is
+  `launch-failed`, in which case `exitCode` will be a platform-specific
+  launch failure error code.