Remove Rust 1.79.0 section from Anchor installation

[acheroncrypto]

Problem

The section about the problem mentioned in otter-sec/anchor#3143 is now resolved (otter-sec/anchor#3315), which made the following section redundant:

developer-content/docs/intro/installation.md

Lines 366 to 400 in 74cc35d

	If you encounter the error `type annotations needed for Box<_>` when installing
	the Anchor CLI, try changing your Rust version to 1.79.0 and attempt the
	installation again.
	<Accordion>
	<AccordionItem title={"error[E0282]: type annotations needed for `Box<_>`"}>
	```
	Compiling time v0.3.29
	error[E0282]: type annotations needed for `Box<_>`
	--> /home/x/.cargo/registry/src/index.crates.io-6f17d22bba15001f/time-0.3.29/src/format_description/parse/mod.rs:83:9
	|
	83 | let items = format_items
	| ^^^^^
	...
	86 | Ok(items.into())
	| ---- type must be known at this point
	|
	help: consider giving `items` an explicit type, where the placeholders `_` are specified
	|
	83 | let items: Box<_> = format_items
	| ++++++++
	```
	You can find more context regarding this error
	[here](https://github.com/coral-xyz/anchor/pull/3143)
	</AccordionItem>
	</Accordion>
	Run the following command to install Rust 1.79.0:
	```shell
	rustup default 1.79.0
	```

Summary of changes

Remove all references to Rust 1.79.0 installation from the Anchor installation section.