README.md: make installation commands directly runnable

[rhythm16]

Allow users to directly copy and run the installation commands.

[masatake]

Thank you for the suggestion.

But such a user should install a binary package on the system one's using or install a prebuilt executable from https://github.com/universal-ctags/ctags-nightly-build.

I added $ to the lines to represent you can build ctags without root privilege.

A change like s/\$ make install/# make install/ makes sense.

[masatake]

+ ./configure  # use --prefix=/where/you/want to override installation directory, defaults to /usr/local

This change is helpful. Could you make a pull request for this line?

[rhythm16]

I added $ to the lines to represent you can build ctags without root privilege.

Ah, I see.

A change like s/\$ make install/# make install/ makes sense.

After your explanation I feel it is better to leave this unchanged, since some users won't have root access, and it's obvious one needs root privileges to install in system directories.

+ ./configure  # use --prefix=/where/you/want to override installation directory, defaults to /usr/local

This change is helpful. Could you make a pull request for this line?

Sure, see #3835 .

Thanks for the feedback.