fix(enterprise-teams): use read-only language in data source Descriptions

Replace "Lists..." with "Retrieves information about..." in:
- data_source_github_enterprise_teams.go
- data_source_github_enterprise_team_organizations.go

Data sources are read-only; their Description must not imply mutation.
Consistent with provider conventions and reviewer feedback on upstream
PR #3008.

Closes #24

Author: vmvarela

github/data_source_github_enterprise_team_organizations.go

@@ -11,7 +11,7 @@ import (
 
 func dataSourceGithubEnterpriseTeamOrganizations() *schema.Resource {
 	return &schema.Resource{
-		Description: "Lists organizations assigned to a GitHub enterprise team.",
+		Description: "Retrieves information about organizations assigned to a GitHub enterprise team.",
 		ReadContext: dataSourceGithubEnterpriseTeamOrganizationsRead,
 
 		Schema: map[string]*schema.Schema{

github/data_source_github_enterprise_teams.go

@@ -20,7 +20,7 @@ const (
 
 func dataSourceGithubEnterpriseTeams() *schema.Resource {
 	return &schema.Resource{
-		Description: "Lists all GitHub enterprise teams in an enterprise.",
+		Description: "Retrieves information about all GitHub enterprise teams in an enterprise.",
 		ReadContext: dataSourceGithubEnterpriseTeamsRead,
 
 		Schema: map[string]*schema.Schema{