Rename aws-cost to aws_cost to match existing naming convention

- Change function name from aws-cost to aws_cost
- Update README documentation to reflect correct function name
- Maintains consistency with other AWS plugin functions that use underscores

plugins/aws/README.md

@@ -35,7 +35,7 @@ plugins=(... aws)
 
 * `aws_change_access_key`: changes the AWS access key of a profile.
 
-* `aws-cost`: displays a quick overview of AWS costs including current month spending, 
+* `aws_cost`: displays a quick overview of AWS costs including current month spending, 
   cost breakdown by service, and comparison with previous periods.
 
 * `aws_profiles`: lists the available profiles in the  `$AWS_CONFIG_FILE` (default: `~/.aws/config`).

plugins/aws/aws.plugin.zsh

@@ -221,7 +221,7 @@ function aws_change_access_key() {
   aws --no-cli-pager iam list-access-keys
 }
 
-function aws-cost() {
+function aws_cost() {
   # Check if AWS CLI is available
   if ! command -v aws &> /dev/null; then
     echo "${fg[red]}AWS CLI not found. Please install AWS CLI v2.${reset_color}" >&2