Improve error message for DataFrame.append(<dict-like>)
#### Code Sample, a copy-pastable example if possible

```python
>>> import pandas as pd
>>>
>>> pd.__version__
'0.26.0.dev0+1731.g3ddd495e4'
>>>
>>> df = pd.DataFrame({"Name": ["Alice"], "Gender": ["F"]})
>>> df
    Name Gender
0  Alice      F
>>>
>>> df.append({"Name": "Bob", "Gender": "M"})
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Users\simon\pandas\pandas\core\frame.py", line 7013, in append
    "Can only append a Series if ignore_index=True "
TypeError: Can only append a Series if ignore_index=True or if the Series has a name

>>>

```
#### Problem description
dict-like is valid type for `other` parameter of DataFrame.append

#### Expected Output

ValueError: Can only append a dict-like if ignore_index=True

#### Output of ``pd.show_versions()``

<details>

[paste the output of ``pd.show_versions()`` here below this line]

</details>
