core-tutorial.txt: Fix argument mistake in an example.

One of examples has wrong output given the arguments provided.
Fix arguments to match the output.

Fix a minor syntax mistake in another place.
Signed-off-by: NSergei Organov <osv@javad.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/core-tutorial.txt

@@ -1149,7 +1149,7 @@ back to the earlier repository with "hello" and "example" file,
 and bring ourselves back to the pre-merge state:
 
 ------------
-$ git show-branch --more=3 master mybranch
+$ git show-branch --more=2 master mybranch
 ! [master] Merge work in mybranch
  * [mybranch] Merge work in mybranch
 --
@@ -1212,7 +1212,7 @@ $ git-read-tree -m -u $mb HEAD mybranch
 This is the same `git-read-tree` command we have already seen,
 but it takes three trees, unlike previous examples.  This reads
 the contents of each tree into different 'stage' in the index
-file (the first tree goes to stage 1, the second stage 2,
+file (the first tree goes to stage 1, the second to stage 2,
 etc.).  After reading three trees into three stages, the paths
 that are the same in all three stages are 'collapsed' into stage
 0.  Also paths that are the same in two of three stages are