Incomplete Documentation for Public Methods

### Incomplete Documentation for Public Methods

**Severity**: Low  
**Files**: 
- [client.go](civogo/client.go)
- [instance.go](civogo/instance.go)

#### Description
Several public methods lack proper Go doc comments explaining their purpose and parameters.

#### Examples:
- `NewAdvancedClientForTesting` ([client.go:106](civogo/client.go:106))
- `UpdateInstanceBandwidth` ([instance.go:479](civogo/instance.go:479))

#### Suggested Fix
Add comprehensive Go doc comments to all public methods following Go conventions:
```go
// NewAdvancedClientForTesting creates a client for testing with custom responses
// responses: A slice of ConfigAdvanceClientForTesting defining expected requests and responses
// Returns a Client instance, test server, and error
```

**Labels**: documentation, improvement

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Incomplete Documentation for Public Methods #279