Add minor changes to style guides

## Emphasis

Markdown treats asterisks (_*_) as indicators of emphasis.

Markdown treats asterisks (_*_) indicators of emphasis,

and renders text marked up like this in italics.

We use emphasis

- to highlight a word, phrase, or character where it is itself the object of discussion.

  For example,

  ~~~

  we want to output the lines that do not contain the word *the*.

  We want to output the lines that do not contain the word *the*.

  ~~~

  This is preferable instead of the use of quotation marks.

  See the "Keyboard Key" section for characters or keyboard keys that the learn should type.

- for words and phrases that are still regarded as foreign.

- for words and phrases that are still regarded as unfamiliar.

- for titles of books, periodicals, plays, films, TV, radio series, and music albums.

  For example,

  ~~~

  we will use a file that contains three haikus taken from a 1998 competition in *Salon* magazine.

  We will use a file that contains three haikus taken from a 1998 competition in *Salon* magazine.

  ~~~

## Strong Emphasis

Markdown treats double asterisks (_**_) as indicators of strong emphasis.

Markdown treats double asterisks (_**_) as indicators of strong emphasis,

and renders text marked up like this in boldface.

We use strong emphasis

- to highlight a newly introduced term, often one that is going to be defined or explained.

  we don't use span of code. For example,

  ~~~

  The most popular Unix shell is Bash

  The most popular Unix shell is Bash.

  ~~~

- to highlight one function where it is itself the object of discussion.

  For example,

  ~~~

  `len` is much faster than any function we could write ourselves

  `len` is much faster than any function we could write ourselves.

  ~~~

- to highlight one file name where it is itself the object of discussion.