Fix database typo in the usage: list all entries in the local databse

[nicokosi]

What does it do?

It fixes a typo in the usage, see list all entries in the local databse in:

$ tldr
usage: tldr [-v] [OPTION]... SEARCH

available commands:
    -v                   print verbose output
    --version            print version and exit
    -h, --help           print this help and exit
    -u, --update         update local database
    -c, --clear-cache    clear local database
    -l, --list           list all entries in the local databse
    -p, --platform=PLATFORM select platform, supported are linux / osx / sunos / windows / common
    --linux              show command page for Linux
    --osx                show command page for OSX
    --sunos              show command page for SunOS
    -r, --render=PATH    render a local page for testing purposes

tldr --version
tldr v1.4.3 (v1.4.3)
Copyright (C) 2016 Arvid Gerstmann
Source available at https://github.com/tldr-pages/tldr-c-client

Why the change?

Typos should be avoided. 😉

How can this be tested?

Run tldr and check the output. 👁️

Where to start code review?

Should be easy. 😉

Relevant tickets?

None.

Questions?

No.