Add usage section.

content/docs/usage/_index.en.md

@@ -0,0 +1,79 @@
+---
+title: "Usage"
+weight: 1
+# bookFlatSection: false
+# bookToc: true
+# bookHidden: false
+# bookCollapseSection: false
+# bookComments: true
+---
+
+# Usage
+
+{{< hint info >}}
+Refer the corresponding subsections (in the side menu) for usage examples and explanations. This section deals with terminologies and usage of command line tools in general.
+{{< /hint >}}
+
+Running the command `cpt --help` produces the following.
+```text
+Lightweight cli tool for competitive programming!
+
+Usage:
+  cpt [command]
+
+Available Commands:
+  codeforces  Functions exclusive to codeforces
+  config      Configure global settings
+  generate    Create file using template
+  help        Help about any command
+  test        Run code file against sample tests
+  upgrade     Upgrade cli to latest version
+
+Flags:
+  -h, --help      help for cpt
+  -v, --version   version for cpt
+
+Use "cpt [command] --help" for more information about a command.
+```
+
+# Anatomy
+
+A typical command line interface has the following usage pattern:
+```text
+APPNAME COMMAND ARGUMENT --FLAG
+```
+
+**Commands** represent actions, **Arguments** are things and **Flags** are modifiers of those actions.
+
+In the above help message, 'config' is a command, and 'version' is a flag.
+
+## Command
+
+A command is the central point of the application. Each interaction that the application supports will be encapsulated within a command. A command can have children commands and can optionally run an action.
+
+In the following example,
+```text
+cpt codeforces config
+```
+'codeforces' is a command, and 'config' is a subcommand of 'codeforces'.
+
+## Flag
+
+A command line flag (also known as an option or switch) modifies the operation of a command. They are preceeded by two hyphens, and in the case of short flags (containing only a single character) they are preceeded by a single hyphen.
+
+Flags are non-positional, that is, they can be specified anywhere **after the command** is called. Flags may take an optional value (seperated by a equal sign), or act as a switch (boolean flag). 
+
+A valid flag usage example is given below.
+```text
+cpt test --mode=i -f=test.cpp
+```
+
+## Argument
+
+A command line argument is an item of information provided to a program when it is started. A program can have many command line arguments that identify sources or destinations of information, or that alter the operation of the program.
+
+```text
+cpt codeforces fetch 1123 c
+```
+Here, '1123' and 'c' are positional arguments.
+

content/menu/_index.en.md

@@ -6,5 +6,6 @@ headless: true
 - [**Setup**]({{< relref "/docs/setup" >}})
   - [Browser]({{< relref "/docs/setup/browser" >}})
   - [Template]({{< relref "/docs/setup/template" >}})
+- [**Usage**]({{< relref "/docs/usage" >}})
 
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