Merge branch 'ta/glossary' into maint

* ta/glossary:
  glossary: improve definitions of refspec and pathspec
  The name of the hash function is "SHA-1", not "SHA1"
  glossary: improve description of SHA-1 related topics
  glossary: remove outdated/misleading/irrelevant entries

diff --cc Documentation/glossary-content.txt
index 2478a3963cc774f1bf73c56660a2d4c096ad4d94,740bb325bf8006340c30659e58a76ac84f47b851..ce3e4fae731b6c6c4e67034393309cd20f69b7dc
--- 1/Documentation/glossary-content.txt
--- 2/Documentation/glossary-content.txt
+++ b/Documentation/glossary-content.txt
@@@ -100,26 -100,10 +100,23 @@@ to point at the new commit
  
  [[def_detached_HEAD]]detached HEAD::
        Normally the <<def_HEAD,HEAD>> stores the name of a
 -      <<def_branch,branch>>.  However, Git also allows you to <<def_checkout,check out>>
 -      an arbitrary <<def_commit,commit>> that isn't necessarily the tip of any
 -      particular branch.  In this case HEAD is said to be "detached".
 +      <<def_branch,branch>>, and commands that operate on the
 +      history HEAD represents operate on the history leading to the
 +      tip of the branch the HEAD points at.  However, Git also
 +      allows you to <<def_checkout,check out>> an arbitrary
 +      <<def_commit,commit>> that isn't necessarily the tip of any
 +      particular branch.  The HEAD in such a state is called
 +      "detached".
 ++
 +Note that commands that operate on the history of the current branch
 +(e.g. `git commit` to build a new history on top of it) still work
 +while the HEAD is detached. They update the HEAD to point at the tip
 +of the updated history without affecting any branch.  Commands that
 +update or inquire information _about_ the current branch (e.g. `git
 +branch --set-upstream-to` that sets what remote tracking branch the
 +current branch integrates with) obviously do not work, as there is no
 +(real) current branch to ask about in this state.
  
- [[def_dircache]]dircache::
-       You are *waaaaay* behind. See <<def_index,index>>.
- 
  [[def_directory]]directory::
        The list you get with "ls" :-)