docs: remove external project and issue references from README

Keep the README self-contained by dropping links to other repositories' issue trackers and design-reference projects, which are internal context rather than user-facing documentation.

- Drop the design-reference links to `foundry-rs/foundry-toolchain` and `actions-rust-lang/setup-rust-toolchain` from the intro
- Drop the `edgeandnode/amp#1383` and `edgeandnode/amp#2600` issue links from the installable-components note

Signed-off-by: Lorenzo Delgado <lorenzo@edgeandnode.com>

Author: LNSD

README.md

@@ -20,9 +20,7 @@ itself, `ampd`, `ampctl`, and `ampsql` (when included in the release) are on
 
 This action is a thin composite wrapper around the same install path the
 documentation recommends (`https://ampup.sh/install` followed by
-`ampup install`), so CI behaves exactly like a local install. Its design
-follows [`foundry-rs/foundry-toolchain`](https://github.com/foundry-rs/foundry-toolchain)
-and [`actions-rust-lang/setup-rust-toolchain`](https://github.com/actions-rust-lang/setup-rust-toolchain).
+`ampup install`), so CI behaves exactly like a local install.
 
 ## Example workflows
 
@@ -176,9 +174,7 @@ The action honors two environment variables:
   `ampup` invocations in later steps need an explicit `--repo` flag.
 
 Installable components (e.g. PostgreSQL for `ampd solo`, ADBC drivers) will
-be supported through this action once `ampup` ships component management
-(see [edgeandnode/amp#1383](https://github.com/edgeandnode/amp/issues/1383)
-and [edgeandnode/amp#2600](https://github.com/edgeandnode/amp/issues/2600)).
+be supported through this action once `ampup` ships component management.
 
 ## Contributing