Initial content for Symfony performance integrations

[PeloWriter]

Adding initial content to cover the Symfony tracing after a brief convo with @HazAT. Related to #3463,

Fixes #3463

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🔍 Inspect: https://vercel.com/sentry/sentry-docs/HhRVsYAo4m9WAHggKjaZo9cBZ5HQ
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[Jean85]

There's one common misconception: tracing is enabled by default.

Apart from that, I find the current structure of the guide for Symfony confusing: there's Config and Configuration sections, there's constant cross-reference to content related to the generic PHP SDK, there's no line between what's responsibility of the Symfony bundle and what belongs to the base SDK...

[PeloWriter]

I'm checking this file, and see that enabled is set to false, which is why the content says it is disabled by default.

The structure issue requires a larger investigation, thanks for raising it.

[ste93cry]

I'm checking this file, and see that enabled is set to false, which is why the content says it is disabled by default.

Sorry, that's just a fixture file used for the tests. As soon as the conditions for each integration to be enabled are satisfied the integration is automatically enabled

[PeloWriter]

Got it. Thanks for clarifying. I'll modify appropriately.

[PeloWriter]

I've also added an issue to track the need to unknot the confusion between Symfony and PHP.

[PeloWriter]

@ste93cry - can you please review with the updated samples? Many thanks.

[PeloWriter]

Got it. I've updated to:

"E_ALL defaults to the value returned by the error_reporting() function, which can change at runtime. Alternately, you can set the option to a fixed value by setting error_types to a different constant in \Sentry\init(). In this case, Sentry will log errors of that specific type regardless of the current reporting level."

[ste93cry]

It's still wrong. Here the corrected version:

By default, the error_types option defaults to the value returned by the error_reporting() function, which can change at runtime. Alternately, you can set the option to a fixed value by setting its value to a bitmask of the PHP E_* constants in \Sentry\init(). In this case, Sentry will log only errors of those specific types regardless of the current reporting level.

[HazAT]

I think this is good enough to merge for now.