[Docs] Fix typos, improve, update at Using Diffusers' Tecniques page

[tolgacangoz]

What does this PR do?

Fix typos, improve, update; add visualizations.

Stable Diffusion Conceptualizer -> Runtime error:

• https://huggingface.co/docs/diffusers/main/en/using-diffusers/textual_inversion_inference#:~:text=concepts%20in%20the-,Stable%20Diffusion%20Conceptualizer,-.
• https://huggingface.co/docs/diffusers/main/en/using-diffusers/weighted_prompts#:~:text=Stable%20Diffusion%20Conceptualizer

Wandb link: "It looks like you’ve landed on a locked or empty page.":

• https://huggingface.co/docs/diffusers/main/en/using-diffusers/freeu#:~:text=Comes%20from%20%0A%23-,https%3A//wandb.ai,-/nasirk24/UNET%2DFreeU

@stevhliu @yiyixuxu @DN6

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[stevhliu]

Thanks for the update, we'll work on fixing the Stable Diffusion Conceptualizer!

cc @kadirnar, do you know if it'd be possible to get access to the wandb report linked in the FreeU doc?