Add usage example to README

Author: giordano

README.md

@@ -11,3 +11,54 @@
 
 This package lets you capture subprocess `stdout` and `stderr` streams
 independently, resynthesizing and colorizing the streams appropriately.
+
+## Installation
+
+`OutputCollectors.jl` can be installed with [Julia built-in package
+manager](https://julialang.github.io/Pkg.jl/v1/).  In a Julia session, after
+entering the package manager mode with `]`, run the command
+
+```
+add OutputCollectors.jl
+```
+
+## Usage
+
+```julia
+julia> using OutputCollectors
+
+julia> script = """
+       #!/bin/sh
+       echo 1
+       sleep 1
+       echo 2 >&2
+       sleep 1
+       echo 3
+       sleep 1
+       echo 4
+       """
+"#!/bin/sh\necho 1\nsleep 1\necho 2 >&2\nsleep 1\necho 3\nsleep 1\necho 4\n"
+
+julia> oc = OutputCollector(`sh -c $script`; verbose = true);
+
+julia> [22:42:30] 1
+[22:42:31] 2
+[22:42:32] 3
+[22:42:33] 4
+julia>
+
+julia> merge(oc)
+"1\n2\n3\n4\n"
+
+julia> merge(oc; colored = true)
+"1\n\e[31m2\n\e[39m3\n4\n"
+
+julia> tail(oc; len = 2)
+"3\n4\n"
+
+julia> collect_stdout(oc)
+"1\n3\n4\n"
+
+julia> collect_stderr(oc)
+"2\n"
+```