Improve documentation on how to use Ionicons

### Current Behavior

Going through the issues I've seen the following theme that mostly indicates a lack of documentation on how to use Ionicons properly:

- https://github.com/ionic-team/ionicons/issues/877
- differentiate between lazy build and custom element, maybe remove lazy all together, refs #1441
- document how to integrate into Angular #1340
- document how to integrate into Reach https://github.com/ionic-team/ionicons/issues/835
- document how to integrate into Vue https://github.com/ionic-team/ionicons/issues/1043
- document how to integate when using esbuild #1435
- integration into [storybook](https://github.com/ionic-team/ionicons/issues/670)
- bundling icons for offline use [#821](https://github.com/ionic-team/ionicons/issues/821)
- Using with a bundle https://github.com/ionic-team/ionicons/issues/1133, https://github.com/ionic-team/ionicons/issues/648, https://github.com/ionic-team/ionicons/issues/774, https://github.com/ionic-team/ionicons/issues/751
- document how to enable SSR support (https://github.com/ionic-team/ionicons/issues/1404, https://github.com/ionic-team/ionicons/issues/886)
- usage of custom icons https://github.com/ionic-team/ionicons/issues/535, https://github.com/ionic-team/ionicons/issues/1013, https://github.com/ionic-team/ionicons/issues/589

### Expected Behavior

Update the documentation to respect modern stacks and tools. Make changes in necessary to improve the DX.

### Steps to Reproduce

n/a

### Code Reproduction URL

_No response_

### Additional Information

_No response_

Review the existing Ionicons documentation and the linked issues for Angular, bundling, Storybook, SSR, offline use, and custom icons. Define a focused documentation plan for the integrations covered, then verify that each listed use case has clear setup guidance and modern-stack examples.

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