git-sparse-checkout.txt: shuffle some sections and mark as internal

With cone mode as the default, it makes sense to discuss it before
non-cone mode.  Also, the new default means we can just use directories
in most cases and users do not need to understand patterns or their
meanings.  Let's take advantage of this to mark several sections as
"INTERNALS", notifying the user that they do not need to know all those
details in order to make use of the sparse-checkout command.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-sparse-checkout.txt

@@ -73,8 +73,8 @@ to be enabled.
 When `--no-cone` is passed, the input list is considered a list of
 patterns.  This mode is harder to use and less performant, and is thus
 not recommended.  See the "Sparse Checkout" section of
-linkgit:git-read-tree[1] and the "Pattern Set" sections below for more
-details.
+linkgit:git-read-tree[1] and the "Internals...Pattern Set" sections
+below for more details.
 +
 Use the `--[no-]sparse-index` option to use a sparse index (the
 default is to not use it).  A sparse index reduces the size of the
@@ -136,8 +136,8 @@ paths to pass to a subsequent 'set' or 'add' command.  However,
 the disable command, so the easy restore of calling a plain `init`
 decreased in utility.
 
-SPARSE CHECKOUT
----------------
+INTERNALS -- SPARSE CHECKOUT
+----------------------------
 
 "Sparse checkout" allows populating the working directory sparsely.  It
 uses the skip-worktree bit (see linkgit:git-update-index[1]) to tell Git
@@ -161,24 +161,8 @@ To repopulate the working directory with all files, use the
 `git sparse-checkout disable` command.
 
 
-FULL PATTERN SET
-----------------
-
-By default, the sparse-checkout file uses the same syntax as `.gitignore`
-files.
-
-While `$GIT_DIR/info/sparse-checkout` is usually used to specify what
-files are included, you can also specify what files are _not_ included,
-using negative patterns. For example, to remove the file `unwanted`:
-
-----------------
-/*
-!unwanted
-----------------
-
-
-CONE PATTERN SET
-----------------
+INTERNALS -- CONE PATTERN SET
+-----------------------------
 
 The full pattern set allows for arbitrary pattern matches and complicated
 inclusion/exclusion rules. These can result in O(N*M) pattern matches when
@@ -256,8 +240,24 @@ use `git add` and `git commit` to store them, then remove any remaining files
 manually to ensure Git can behave optimally.
 
 
-SUBMODULES
-----------
+INTERNALS -- FULL PATTERN SET
+-----------------------------
+
+By default, the sparse-checkout file uses the same syntax as `.gitignore`
+files.
+
+While `$GIT_DIR/info/sparse-checkout` is usually used to specify what
+files are included, you can also specify what files are _not_ included,
+using negative patterns. For example, to remove the file `unwanted`:
+
+----------------
+/*
+!unwanted
+----------------
+
+
+INTERNALS -- SUBMODULES
+-----------------------
 
 If your repository contains one or more submodules, then submodules
 are populated based on interactions with the `git submodule` command.