cmd: tighten up env var usage sections (#2962)

Also, document OLLAMA_HOST client semantics per command that honors it.
This looks nicer than having a general puprose environment variable
section in the root usage which was showing up after the "addition help
topics" section outputed by Cobra's default template.

It was decided this was easier to work with than using a custom template
for Cobra right now.

cmd/cmd.go

@@ -887,6 +887,14 @@ func versionHandler(cmd *cobra.Command, _ []string) {
 	}
 }
 
+func appendHostEnvDocs(cmd *cobra.Command) {
+	const hostEnvDocs = `
+Environment Variables:
+      OLLAMA_HOST        The host:port or base URL of the Ollama server (e.g. http://localhost:11434)
+`
+	cmd.SetUsageTemplate(cmd.UsageTemplate() + hostEnvDocs)
+}
+
 func NewCLI() *cobra.Command {
 	log.SetFlags(log.LstdFlags | log.Lshortfile)
 	cobra.EnableCommandSorting = false
@@ -952,7 +960,6 @@ func NewCLI() *cobra.Command {
 	runCmd.Flags().Bool("insecure", false, "Use an insecure registry")
 	runCmd.Flags().Bool("nowordwrap", false, "Don't wrap words to the next line automatically")
 	runCmd.Flags().String("format", "", "Response format (e.g. json)")
-
 	serveCmd := &cobra.Command{
 		Use:     "serve",
 		Aliases: []string{"start"},
@@ -963,20 +970,9 @@ func NewCLI() *cobra.Command {
 	serveCmd.SetUsageTemplate(serveCmd.UsageTemplate() + `
 Environment Variables:
 
-	OLLAMA_HOST
-		The host:port to bind to (default "127.0.0.1:11434")
-
-		Examples:
-			"127.0.0.1:11434"
-	OLLAMA_ORIGINS
-		A comma separated list of allowed origins. If unset, the
-		default behavior is to allow same origin requests, only.
-
-		Examples:
-			"localhost:11434"
-			"example.com,api.example.com"
-	OLLAMA_MODELS
-		The path to the models directory (default is "~/.ollama/models")
+    OLLAMA_HOST       The host:port to bind to (default "127.0.0.1:11434")
+    OLLAMA_ORIGINS    A comma separated list of allowed origins.
+    OLLAMA_MODELS     The path to the models directory (default is "~/.ollama/models")
 `)
 
 	pullCmd := &cobra.Command{
@@ -1022,6 +1018,19 @@ Environment Variables:
 		RunE:    DeleteHandler,
 	}
 
+	for _, cmd := range []*cobra.Command{
+		createCmd,
+		showCmd,
+		runCmd,
+		pullCmd,
+		pushCmd,
+		listCmd,
+		copyCmd,
+		deleteCmd,
+	} {
+		appendHostEnvDocs(cmd)
+	}
+
 	rootCmd.AddCommand(
 		serveCmd,
 		createCmd,