couple minor formatting fixes

[sogaiu]

@uvtc Regarding line 37, if PREFIX=/usr, I wonder how likely it would be for sudo to be optional.

[uvtc]

I made it consistent with the other two uses in the same section. My hunch is that it's written as "$ [sudo] ..." because you might not be using sudo --- rather, you might be installing as root. But you wouldn't want to include both styles in the instructions,

$ sudo janet bootstrap.janet
# janet bootstrap.janet

so $ [sudo] janet bootstrap.janet is a good compromise.

[sogaiu]

@uvtc I also think that [sudo] means that use of sudo would be optional.

I don't think the proposed line:

$ [sudo] PREFIX=/usr janet bootstrap.janet

is a good compromise because using /usr is not likely to make sense for installation purposes if you don't have the appropriate priviliges.

I think better alternatives include either just:

$ PREFIX=$HOME/.local janet bootstrap.janet

or multiple alternatives (saying before it something like "using something like one of the following"):

$ PREFIX=$HOME/.local janet bootstrap.janet

$ sudo PREFIX=/usr janet bootstrap.janet

[uvtc]

@sogaiu , thanks. Sorry for the delay. I'm not really familiar with the bootstrapping process. My PR was only for a couple of consistency and formatting tweaks.

[sogaiu]

@uvtc No worries :)