Add crypto, forex, and indices examples

[justinpolygon]

Added example code snippets for crypto, forex, and indices.

[justinpolygon]

@jbonzo FYI - it looks like it's actually the linter that made the changes and added the spacing across the lines. So, I changed the code like we chatted about to be:

>                 percent_change = ((item.prev_day.close - item.prev_day.open)/item.prev_day.open*100)
>                 print("{:<15}{:<15}{:<15}{:.2f} %".format(item.ticker,item.prev_day.open,item.prev_day.close,percent_change))

Then, the link check failed here https://github.com/polygon-io/client-python/actions/runs/4601386532/jobs/8129177080?pr=415 so I run poetry run black polygon test_* examples to make the suggested changes and it give me this:

<                 percent_change = (
<                     (item.prev_day.close - item.prev_day.open)
<                     / item.prev_day.open
<                     * 100
<                 )
<                 print(
<                     "{:<15}{:<15}{:<15}{:.2f} %".format(
<                         item.ticker,
<                         item.prev_day.open,
<                         item.prev_day.close,
<                         percent_change,
<                     )
<                 )

[jbonzo]

@jbonzo FYI - it looks like it's actually the linter that made the changes and added the spacing across the lines. So, I changed the code like we chatted about to be:

>                 percent_change = ((item.prev_day.close - item.prev_day.open)/item.prev_day.open*100)

>                 print("{:<15}{:<15}{:<15}{:.2f} %".format(item.ticker,item.prev_day.open,item.prev_day.close,percent_change))

Then, the link check failed here https://github.com/polygon-io/client-python/actions/runs/4601386532/jobs/8129177080?pr=415 so I run poetry run black polygon test_* examples to make the suggested changes and it give me this:

<                 percent_change = (

<                     (item.prev_day.close - item.prev_day.open)

<                     / item.prev_day.open

<                     * 100

<                 )

<                 print(

<                     "{:<15}{:<15}{:<15}{:.2f} %".format(

<                         item.ticker,

<                         item.prev_day.open,

<                         item.prev_day.close,

<                         percent_change,

<                     )

<                 )

Ah. Thats unfortunate. Ok then.