Fix the terraform function name (#6418)

* Fix the terraform function name

Current function name do worse. I always use `terr<TAB>` and before those prompt it was add space in the end. Now because we have multiple functions and binaries started with terraform there are no space.

* Updated terraform readme

Updated the name of new function name

plugins/terraform/terraform.plugin.zsh

@@ -1,4 +1,4 @@
-function terraform_prompt_info() {
+function tf_prompt_info() {
     # check if in terraform dir
     if [ -d .terraform ]; then
       workspace=$(terraform workspace show 2> /dev/null) || return