patchdocs: correct mistakes in git-merge

> From: Timur Sultanaev <str.write@gmail.com>
> 
> Documentation for git-merge incorrectly notes that
> tip of the current branch on ascii diagram is C
> , while it is actually G (current branch is
> master, HEAD on diagram is G).
> 
> Additionally diagrams on the page are adjusted
> to use spaces instead of tabs, so that they align
> regardless of tab size. This is in line with
> diagrams on other git documentation pages.

> Signed-off-by: Timur Sultanaev <str.write@gmail.com>
> ---
>     Correct mistakes in git-merge documentation
> 
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1940%2Fstrowk%2Fmaster-v1
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1940/strowk/master-v1
> Pull-Request: https://github.com/gitgitgadget/git/pull/1940
> 
>  Documentation/git-merge.adoc | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/git-merge.adoc b/Documentation/git-merge.adoc
> index d53923c3b73..a055384ad69 100644
> --- a/Documentation/git-merge.adoc
> +++ b/Documentation/git-merge.adoc
> @@ -28,8 +28,8 @@ Assume the following history exists and the current branch is
>  `master`:
>  
>  ------------
> -	  A---B---C topic
> -	 /
> +          A---B---C topic
> +         /

>      D---E---F---G master
>  ------------
>  
> @@ -38,11 +38,11 @@ Then `git merge topic` will replay the changes made on the
>  its current commit (`C`) on top of `master`, and record the result
>  in a new commit along with the names of the two parent commits and
>  a log message from the user describing the changes. Before the operation,
> -`ORIG_HEAD` is set to the tip of the current branch (`C`).
> +`ORIG_HEAD` is set to the tip of the current branch (`G`).

>  
>  ------------
> -	  A---B---C topic
> -	 /         \
> +          A---B---C topic
> +         /         \
>      D---E---F---G---H master
>  ------------
>  
> 
> base-commit: 8b6f19ccfc3aefbd0f22f6b7d56ad6a3fc5e4f37
> -- 
> gitgitgadget
> 
> 

>> Additionally diagrams on the page are adjusted
>> to use spaces instead of tabs, so that they align
>> regardless of tab size. This is in line with
>> diagrams on other git documentation pages.
>
> To be precise, you could add to the commit message that the faulty
> description was introduced in 0c514d576685 (git-merge.txt: mention
> 'ORIG_HEAD' in the Description, 2023-01-10). (I Cc:ed Philippe Blain who
> authored that patch.)
> ...
>>  ------------
>> -	  A---B---C topic
>> -	 /
>> +          A---B---C topic
>> +         /
>
> ... while correcting the description seemed fairly straight-forward, this
> white-space change appears to tread on more delicate territory. It might
> deserve its own patch
> ...
>> @@ -38,11 +38,11 @@ Then `git merge topic` will replay the changes made on the
>>  its current commit (`C`) on top of `master`, and record the result
>>  in a new commit along with the names of the two parent commits and
>>  a log message from the user describing the changes. Before the operation,
>> -`ORIG_HEAD` is set to the tip of the current branch (`C`).
>> +`ORIG_HEAD` is set to the tip of the current branch (`G`).
>
> This is obviously a good fix.