doc(install): Tell users about foo@version syntax

Author: epage

src/doc/man/cargo-install.md

@@ -8,7 +8,7 @@ cargo-install - Build and install a Rust binary
 
 ## SYNOPSIS
 
-`cargo install` [_options_] _crate_...\
+`cargo install` [_options_] _crate_[@_version_]...\
 `cargo install` [_options_] `--path` _path_\
 `cargo install` [_options_] `--git` _url_ [_crate_...]\
 `cargo install` [_options_] `--list`

src/doc/man/generated_txt/cargo-install.txt

@@ -4,7 +4,7 @@ NAME
        cargo-install - Build and install a Rust binary
 
 SYNOPSIS
-       cargo install [options] crate...
+       cargo install [options] crate[@version]...
        cargo install [options] --path path
        cargo install [options] --git url [crate...]
        cargo install [options] --list

src/doc/src/commands/cargo-install.md

@@ -8,7 +8,7 @@ cargo-install - Build and install a Rust binary
 
 ## SYNOPSIS
 
-`cargo install` [_options_] _crate_...\
+`cargo install` [_options_] _crate_[@_version_]...\
 `cargo install` [_options_] `--path` _path_\
 `cargo install` [_options_] `--git` _url_ [_crate_...]\
 `cargo install` [_options_] `--list`

src/etc/man/cargo-install.1

@@ -6,7 +6,7 @@
 .SH "NAME"
 cargo\-install \- Build and install a Rust binary
 .SH "SYNOPSIS"
-\fBcargo install\fR [\fIoptions\fR] \fIcrate\fR\&...
+\fBcargo install\fR [\fIoptions\fR] \fIcrate\fR[@\fIversion\fR]\&...
 .br
 \fBcargo install\fR [\fIoptions\fR] \fB\-\-path\fR \fIpath\fR
 .br