worktree: use 'worktree' over 'working tree'

It is helpful to distinguish between a 'working tree' and a 'worktree'.
A worktree contains a working tree plus additional metadata. This
metadata includes per-worktree refs and worktree-specific config.

This is the sixth of multiple changes to git-worktree.txt, restricted to
the DETAILS section.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-worktree.txt

@@ -319,29 +319,29 @@ linkgit:git-config[1] for more details.
 
 DETAILS
 -------
-Each linked working tree has a private sub-directory in the repository's
+Each linked worktree has a private sub-directory in the repository's
 `$GIT_DIR/worktrees` directory.  The private sub-directory's name is usually
-the base name of the linked working tree's path, possibly appended with a
+the base name of the linked worktree's path, possibly appended with a
 number to make it unique.  For example, when `$GIT_DIR=/path/main/.git` the
 command `git worktree add /path/other/test-next next` creates the linked
-working tree in `/path/other/test-next` and also creates a
+worktree in `/path/other/test-next` and also creates a
 `$GIT_DIR/worktrees/test-next` directory (or `$GIT_DIR/worktrees/test-next1`
 if `test-next` is already taken).
 
-Within a linked working tree, `$GIT_DIR` is set to point to this private
+Within a linked worktree, `$GIT_DIR` is set to point to this private
 directory (e.g. `/path/main/.git/worktrees/test-next` in the example) and
-`$GIT_COMMON_DIR` is set to point back to the main working tree's `$GIT_DIR`
+`$GIT_COMMON_DIR` is set to point back to the main worktree's `$GIT_DIR`
 (e.g. `/path/main/.git`). These settings are made in a `.git` file located at
-the top directory of the linked working tree.
+the top directory of the linked worktree.
 
 Path resolution via `git rev-parse --git-path` uses either
 `$GIT_DIR` or `$GIT_COMMON_DIR` depending on the path. For example, in the
-linked working tree `git rev-parse --git-path HEAD` returns
+linked worktree `git rev-parse --git-path HEAD` returns
 `/path/main/.git/worktrees/test-next/HEAD` (not
 `/path/other/test-next/.git/HEAD` or `/path/main/.git/HEAD`) while `git
 rev-parse --git-path refs/heads/master` uses
 `$GIT_COMMON_DIR` and returns `/path/main/.git/refs/heads/master`,
-since refs are shared across all working trees, except `refs/bisect` and
+since refs are shared across all worktrees, except `refs/bisect` and
 `refs/worktree`.
 
 See linkgit:gitrepository-layout[5] for more information. The rule of
@@ -349,8 +349,8 @@ thumb is do not make any assumption about whether a path belongs to
 `$GIT_DIR` or `$GIT_COMMON_DIR` when you need to directly access something
 inside `$GIT_DIR`. Use `git rev-parse --git-path` to get the final path.
 
-If you manually move a linked working tree, you need to update the `gitdir` file
-in the entry's directory. For example, if a linked working tree is moved
+If you manually move a linked worktree, you need to update the `gitdir` file
+in the entry's directory. For example, if a linked worktree is moved
 to `/newpath/test-next` and its `.git` file points to
 `/path/main/.git/worktrees/test-next`, then update
 `/path/main/.git/worktrees/test-next/gitdir` to reference `/newpath/test-next`
@@ -359,10 +359,10 @@ automatically.
 
 To prevent a `$GIT_DIR/worktrees` entry from being pruned (which
 can be useful in some situations, such as when the
-entry's working tree is stored on a portable device), use the
+entry's worktree is stored on a portable device), use the
 `git worktree lock` command, which adds a file named
 `locked` to the entry's directory. The file contains the reason in
-plain text. For example, if a linked working tree's `.git` file points
+plain text. For example, if a linked worktree's `.git` file points
 to `/path/main/.git/worktrees/test-next` then a file named
 `/path/main/.git/worktrees/test-next/locked` will prevent the
 `test-next` entry from being pruned.  See