Documentation: Minor English errors in tutorial/introduction

[jpgoldberg]

Describe the bug

1. The tutorial introduction uses the "teached" instead of "taught" as the past-participle of "teach". "Teached" is not an English word.
2. "Python do not have a pipe operators" contains two errors

To Reproduce

1. Go to https://expression.readthedocs.io/en/latest/tutorial/introduction.html#pipelining in your favorite browser
2. Look for the sentence

   The main reason for this is that we are teached to read from left to right.

3. observe the word "teached"

Later in that same section is

Python do not have a pipe operators

That should be replaced with

Python does not have a pipe operator

Note that there are two changes in that line. s/do/does/ and s/operators/operator/

Expected behavior

The sentence should be

The main reason for this is that we are taught to read from left to right.

Additional context

The error is near line 250 of docs/tutorial/introduction.md.

[dbrattli]

Thanks. Please make a PR