submodules.asc: clarify DbConnector/try-merge example

Fix AsciiDoc 'source,console' block to render separately the consecutive
commands 'git branch try-merge c771610' and 'git merge try-merge'. This is
accomplished by separating the commands with an empty line, and by omitting
the unneeded "(DbConnector) " prefix in front of the 'git merge...' command
prompt. Puts the example into the form consistent with the other command
blocks, and also enhances readability.

State explicitly in the prose that "try-merge" will be the name of the branch.

Author: salewski

book/07-git-tools/sections/submodules.asc

@@ -605,7 +605,7 @@ This is what you'll have to merge in and resolve.
 You can either just try the merge with the SHA-1 directly, or you can create a branch for it and then try to merge that in.
 We would suggest the latter, even if only to make a nicer merge commit message.
 
-So, we will go into our submodule directory, create a branch based on that second SHA-1 from `git diff` and manually merge.
+So, we will go into our submodule directory, create a branch named ``try-merge'' based on that second SHA-1 from `git diff`, and manually merge.
 
 [source,console]
 ----
@@ -615,7 +615,8 @@ $ git rev-parse HEAD
 eb41d764bccf88be77aced643c13a7fa86714135
 
 $ git branch try-merge c771610
-(DbConnector) $ git merge try-merge
+
+$ git merge try-merge
 Auto-merging src/main.c
 CONFLICT (content): Merge conflict in src/main.c
 Recorded preimage for 'src/main.c'