docs(readme): correct/improve a few typos (#151)

* Correct/improve a few typos

* Add suggestion to use sudo -E

sudo -E inherits current users environment variables

README.md

@@ -54,10 +54,11 @@ cargo install bandwhich
 ```
 
 This installs `bandwhich` to `~/.cargo/bin/bandwhich` but you need root priviliges to run `bandwhich`. To fix that, there are a few options:
-- Give the executable elevated permissions: ``sudo setcap cap_sys_ptrace,cap_dac_read_search,cap_net_raw,cap_net_admin+ep `which bandwhich`` 
+- Give the executable elevated permissions: ``sudo setcap cap_sys_ptrace,cap_dac_read_search,cap_net_raw,cap_net_admin+ep $(which bandwhich)`` 
 - Run `sudo ~/.cargo/bin/bandwhich` instead of just `bandwhich`
 - Create a symlink: `sudo ln -s ~/.cargo/bin/bandwhich /usr/local/bin/` (or another path on root's PATH)
-- Set root's PATH to match your own `sudo env "PATH=$PATH" bandwhich`
+- Set root's PATH to match your own: `sudo env "PATH=$PATH" bandwhich`
+- Tell sudo to use your user's environment variables: `sudo -E bandwhich`
 - Pass the desired target directory to cargo: `sudo cargo install bandwhich --root /usr/local/bin/`
 
 #### Download a prebuilt binary