Add jc function, jump to a subdirectory of the current working directory.

Closes #156.

docs/autojump.1

@@ -4,7 +4,7 @@
 autojump - a faster way to navigate your filesystem
 .SS SYNOPSIS
 .PP
-Jump to a previously visited directory \[aq]foobar\[aq]:
+Jump to a previously visited directory that contains \[aq]foo\[aq]:
 .IP
 .nf
 \f[C]
@@ -12,6 +12,15 @@ j\ foo
 \f[]
 .fi
 .PP
+Jump to a previously visited subdirectory of the current working
+directory:
+.IP
+.nf
+\f[C]
+jc\ bar
+\f[]
+.fi
+.PP
 Show all database entries and their respective key weights:
 .IP
 .nf

docs/header.md

@@ -3,10 +3,14 @@
 autojump - a faster way to navigate your filesystem
 
 ## SYNOPSIS
-Jump to a previously visited directory 'foobar':
+Jump to a previously visited directory that contains 'foo':
 
     j foo
 
+Jump to a previously visited subdirectory of the current working directory:
+
+    jc bar
+
 Show all database entries and their respective key weights:
 
     j --stat