Change bookmark prompt and pin dir keys.

New keys:

- bookmark prompt (^B)
- pin directory (B)

The intention of the change is to facilitate opening the bookmark prompt in
navigate-as-you-type mode. The bookmark prompt is used more than the pin
current directory option.

README.md

@@ -226,8 +226,8 @@ optional arguments:
               / | Filter dir contents
              ^/ | Open desktop search tool
               . | Toggle hide . files
-              b | Bookmark prompt
-             ^B | Pin current dir
+             ^B | Bookmark prompt
+              B | Pin current dir
              ^V | Go to pinned dir
               c | Change dir prompt
               d | Toggle detail view

nnn.1

@@ -62,9 +62,9 @@ Change filter (more information below)
 Search directory in desktop search tool
 .It Ic \&.
 Toggle hide .dot files
-.It Ic b
-Show bookmark key prompt
 .It Ic ^B
+Show bookmark key prompt
+.It Ic B
 Pin current directory
 .It Ic ^V
 Visit pinned directory

nnn.c

@@ -1716,8 +1716,8 @@ show_help(char *path)
 	     "e/ | Filter dir contents\n"
 	    "d^/ | Open desktop search tool\n"
 	     "e. | Toggle hide . files\n"
-	     "eb | Bookmark prompt\n"
-	    "d^B | Pin current dir\n"
+	    "d^B | Bookmark prompt\n"
+	     "eB | Pin current dir\n"
 	    "d^V | Go to pinned dir\n"
 	     "ec | Change dir prompt\n"
 	     "ed | Toggle detail view\n"

nnn.h

@@ -106,9 +106,9 @@ static struct key bindings[] = {
 	/* Last visited dir */
 	{ '-',            SEL_CDLAST,    "",     "" },
 	/* Change dir using bookmark */
-	{ 'b',            SEL_CDBM,      "",     "" },
+	{ CONTROL('B'),   SEL_CDBM,      "",     "" },
 	/* Mark a path to visit later */
-	{ CONTROL('B'),   SEL_PIN,       "",     "" },
+	{ 'B',            SEL_PIN,       "",     "" },
 	/* Visit marked directory */
 	{ CONTROL('V'),   SEL_VISIT,     "",     "" },
 	/* Filter */