Add 'insert' key for --bind

Close #1744

man/man1/fzf.1

@@ -21,7 +21,7 @@ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 ..
-.TH fzf 1 "Dec 2019" "fzf 0.20.0" "fzf - a command-line fuzzy finder"
+.TH fzf 1 "Feb 2020" "fzf 0.21.0" "fzf - a command-line fuzzy finder"
 
 .SH NAME
 fzf - a command-line fuzzy finder
@@ -600,6 +600,8 @@ e.g.
 .br
 \fIend\fR
 .br
+\fIinsert\fR
+.br
 \fIpgup\fR        (\fIpage-up\fR)
 .br
 \fIpgdn\fR        (\fIpage-down\fR)