Add global cooldown info to Library docs (#3307)

[ ] Check if this is a typo or other quick fix and ignore the rest :)

## Type of change
Update to existing pages

### What should this PR do?
Add that the cooldown applies globally to chainguard-built and upstream
packages for JS libraries

### Why are we making this change?
New functionality released

### What are the acceptance criteria? 
Content should be clear and accurate, and appear in the expected
location

### How should this PR be tested?
Review the deploy preview

Signed-off-by: s-stumbo <sally.stumbo@chainguard.dev>

Author: s-stumbo

content/chainguard/chainguard-repository/overview.md

@@ -40,7 +40,7 @@ The Chainguard Repository includes a policy engine that lets you define rules go
 For language dependencies, policies apply to both Chainguard-built packages and upstream packages served via the optional fallback to public registries. Available policies include:
 
 * **Upstream fallback**: Control whether packages not yet built by Chainguard can be sourced from the upstream public registry.  
-* **Cooldown**: When upstream fallback is enabled, block newly published package versions for a defined period before they can be pulled, giving the security community time to detect threats. The cooldown is configurable (0 to 3650 days) with a default of 7 days. 
+* **Cooldown**: When upstream fallback is enabled, block newly published package versions for a defined period before they can be pulled, giving the security community time to detect threats. The cooldown is configurable (0 to 3650 days) with a default of 7 days. It is applied globally across all packages to prevent dependency resolution errors.
 
 > **Note**: Chainguard recommends a 7-day cooldown when enabling upstream fallback, to block a large share of malicious packages identified shortly after publication. Shorter cooldown periods increase the risk of pulling malicious or compromised upstream packages before the broader ecosystem can detect and report them.
 

content/chainguard/libraries/javascript/overview.md

@@ -243,9 +243,10 @@ chainctl libraries entitlements create --ecosystems=JAVASCRIPT --policy=CHAINGUA
 ```
 
 ### Fallback options
+
 The following options are available:
 * **No upstream fallback (default)**: Only Chainguard-built packages are served.
-* **Upstream fallback enabled with cooldown**: Upstream packages are available after passing a cooldown period and malware scan. 
+* **Upstream fallback enabled with cooldown**: Upstream packages are available after passing a cooldown period and malware scan. The same cooldown period is also enforced for Chainguard-built packages when the upstream repository is enabled, so dependency trees resolve consistently across both sources.
 
 #### Configuring the cooldown period
 
@@ -270,6 +271,8 @@ Malware detection is continuous. If a version that was previously cached is late
 
 When fallback is enabled, upstream npm packages are subject to a cooldown period from their publication date before the Chainguard Repository will serve them. The cooldown is an additional layer of security that provides a window for the security community to identify and report malicious packages before your builds can pull them. 
 
+The cooldown applies globally across Chainguard-built packages and upstream npm packages served through the fallback. This prevents installs from failing when a Chainguard-built package depends on an upstream dependency that is still under the cooldown window.
+
 If a package version is requested and falls within the cooldown period, the package manager will output a 404 error. The package becomes available once it has passed the cooldown period and cleared malware scanning.
 
 ### How package resolution works