DOC: Improve the docstring of DataFrame.transpose()
Checklist for the pandas documentation sprint (ignore this if you are doing
an unrelated PR):

- [x] PR title is "DOC: update the <your-function-or-method> docstring"
- [x] The validation script passes: `scripts/validate_docstrings.py <your-function-or-method>`
- [x] The PEP8 style check passes: `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] The html version looks good: `python doc/make.py --single <your-function-or-method>`
- [x] It has been proofread on language by another sprint participant

Please include the output of the validation script below between the "```" ticks:

```
################################################################################
################################## Validation ##################################
################################################################################

Errors found:
	Errors in parameters section
		Parameters {'args', 'kwargs'} not documented
		Unknown parameters {'*args', '**kwargs'}
		Parameter "*args" has no type
		Parameter "**kwargs" has no type
```

The errors are well-known false positives.
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/20254?src=pr&el=h1) Report
> Merging [#20254](https://codecov.io/gh/pandas-dev/pandas/pull/20254?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/85817a72897be808fb6d311f65fc6031e0216603?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/20254/graphs/tree.svg?height=150&src=pr&token=eZ4WkYLtcO&width=650)](https://codecov.io/gh/pandas-dev/pandas/pull/20254?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #20254   +/-   ##
=======================================
  Coverage   91.84%   91.84%           
=======================================
  Files         152      152           
  Lines       49231    49231           
=======================================
  Hits        45215    45215           
  Misses       4016     4016
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.22% <ø> (ø)` | :arrow_up: |
| #single | `41.83% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/20254?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/20254/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.18% <ø> (ø)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/20254?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/20254?src=pr&el=footer). Last update [85817a7...ead247c](https://codecov.io/gh/pandas-dev/pandas/pull/20254?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 (I only made a small clarification of the `copy` keyword, that even if `copy=False` it is not *always* no copy) @igorcadelima @cemsbr Thanks for the PR!