Recommended by Christian Miller.
* doc/guix.texi (Packages with Multiple Outputs): Replace 'a packages'
with 'a package'.
(Invoking guix time-machine): Don't assume knowledge and give an
explicit link to Back to the Future.
(Invoking guix pack): Remove doubled word.
(Build Systems): Same.
(Debugging Build Failures): 'inspect' is not a command to be run.
(Invoking guix import): Remove doubled word.
(Invoking guix size): Remove stray word.
(Invoking guix processes): Replace 'guix environment' with 'guix shell'.
(Base Services): Add missing word.
(Networking Setup): Adjust a/an usage.
(Networking Services): Remove stray symbol. Add space between two
words.
(Desktop Services): Remove stray symbol from example.
(Database Services): Document default postgresql version.
(Web Services): Adjust indentation.
(Audio Services): Add missing newline.
(Miscellaneous Services): Switch 'get' to 'gets'.
(Bootloader Configuration): Remove stray symbol.
(Secure Shell): Remove marks around accepted values.
(Installing Debugging Files): Replace 'is' with 'it'.
(Full-Source Bootstrap): Remove doubled word.
(Preparing to Use the Bootstrap Binaries): Same.
Change-Id: Ifbf2677dff7642c6531384145363d7611286e48b