fix(doc): update missing man pages and doc entry (goharbor#893)

Author: vg006

doc/cli-docs/harbor-repo-update.md

@@ -34,7 +34,7 @@ harbor repo update [flags]
 
 ```sh
   -c, --config string          config file (default is $HOME/.config/harbor-cli/config.yaml)
-  -o, --output-format string   Output format. One of: json|yaml
+  -o, --output-format string   Output format. One of: json|yaml|csv
   -v, --verbose                verbose output
 ```
 

doc/man-docs/man1/harbor-repo-update.1

@@ -37,7 +37,7 @@ Examples:
 
 .PP
 \fB-o\fP, \fB--output-format\fP=""
-	Output format. One of: json|yaml
+	Output format. One of: json|yaml|csv
 
 .PP
 \fB-v\fP, \fB--verbose\fP[=false]