improves conflicts and rebase sections

basics.html

@@ -854,7 +854,8 @@
             ```bash
             git remote add alice https://...
             git fetch alice
-            git merge alice/master
+            git checkout master
+            git merge alice/topic/feature
             # fix conflicts
             git push
             ```
@@ -863,6 +864,7 @@
 
             ```bash
             git fetch upstream
+            git checkout topic/feature
             git merge origin/master
             # fix conflicts
             git push
@@ -919,31 +921,34 @@
             # backup slides
           </section>
 
-          <section id="collab-conflicts-rebase" data-markdown>
+          <section id="collab-rebase-maintainer" data-markdown>
             ## rebasing
-            ### maintainer
+            ### as maintainer
 
             ```bash
             git remote add alice https://...
             git fetch alice
-            git rebase master alice/master
+            git rebase [--interactive] master alice/topic/feature
             # fix conflicts
             git push
-            # close merge request
+            # manually close merge request
             ```
 
-            ### contributor
+            notes:
+            - manually close merge request because no merge commit
+          </section>
+
+          <section id="collab-rebase-contributor" data-markdown>
+            ## rebasing
+            ### as contributor
 
             ```bash
             git fetch upstream
-            git rebase origin/master master
+            git rebase origin/master topic/feature
             # fix conflicts
             # force push because branch history changed
             git push --force
             ```
-
-            notes:
-            - manually close merge request because no merge commit
           </section>
         </section>
       </div>