Improve numerical readability scores for the tutorial. (#546)

Inspired by @paddyroddy 's Vale talk, improving accessibility in
general, and the fun of conforming fuzzy things like language into cold,
hard numbers, I've made a pass at improving some numerical readability
scores for the tutorial document.

In practice, this is me going through and splitting up long sentences,
reducing the use of large words, and trying to say things clearly and
briefly.

Anyone can play around with this themselves using:
```
❯ vale tutorial.md
```
on this branch (with the
[`Readibility`](https://github.com/errata-ai/readability) package
enabled).

On the current `HEAD` of `main`:

```
 1:1      warning  Try to keep the LIX score       Readability.LIX
                   (47.71) below 35.
 1:1      warning  Try to keep the Automated       Readability.AutomatedReadability
                   Readability Index (11.64)
                   below 8.
 1:1      warning  Try to keep the Coleman–Liau    Readability.ColemanLiau
                   Index grade (11.12) below 9.
 1:1      warning  Try to keep the Flesch–Kincaid  Readability.FleschKincaid
                   grade level (11.87) below 8.
 1:1      warning  Try to keep the Gunning-Fog     Readability.GunningFog
                   index (13.52) below 10.
 1:1      warning  Try to keep the SMOG grade      Readability.SMOG
                   (13.25) below 10.
 1:1      warning  Try to keep the Flesch reading  Readability.FleschReadingEase
                   ease score (46.86) above 70.
```

On the `HEAD` of this branch:
```
 1:1     warning  Try to keep the LIX score       Readability.LIX
                  (39.32) below 35.
 1:1     warning  Try to keep the Coleman–Liau    Readability.ColemanLiau
                  Index grade (9.86) below 9.
 1:1     warning  Try to keep the Flesch–Kincaid  Readability.FleschKincaid
                  grade level (8.73) below 8.
 1:1     warning  Try to keep the Gunning-Fog     Readability.GunningFog
                  index (10.73) below 10.
 1:1     warning  Try to keep the SMOG grade      Readability.SMOG
                  (11.24) below 10.
 1:1     warning  Try to keep the Flesch reading  Readability.FleschReadingEase
                  ease score (57.70) above 70.
```

All numbers are better, though most are still "warning" level (we only
lost the ARI).


Now! I'm aware this is coming _very_ close to the tutorial delivery
(sorry!!). So we might want to wait on merging this until afterwards. I
leave it up to you @Saransh-cpp. You're the workshop lead...

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Copilot <[email protected]>
Co-authored-by: Saransh Chopra <[email protected]>

Author: 4 people

.vale.ini

@@ -2,12 +2,14 @@ StylesPath = .github/styles
 
 # https://github.com/errata-ai/packages
 Packages = proselint,\
-           write-good
+           write-good,\
+           Readability
 
 [*.md]
 BasedOnStyles = proselint,\
                 Vale,\
-                write-good
+                write-good,\
+                Readability
 
 # Disable
 Vale.Spelling = NO