DOC: Edit installation instructions for clarity.
Rewrote some lines to ease reading. Didn't change substance.
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19798?src=pr&el=h1) Report
> Merging [#19798](https://codecov.io/gh/pandas-dev/pandas/pull/19798?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/740ad9aabda113e34de0d30c78b8aec40414daf7?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/19798/graphs/tree.svg?height=150&width=650&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/19798?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #19798   +/-   ##
=======================================
  Coverage   91.61%   91.61%           
=======================================
  Files         150      150           
  Lines       48887    48887           
=======================================
  Hits        44786    44786           
  Misses       4101     4101
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.98% <ø> (ø)` | :arrow_up: |
| #single | `41.8% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19798?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/19798?src=pr&el=footer). Last update [740ad9a...5c8948b](https://codecov.io/gh/pandas-dev/pandas/pull/19798?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
