Use imperative mood for example commit messages

Since we recommend this (via the linked article) we ought to do it
ourselves!

_episodes/04-changes.md

@@ -672,12 +672,12 @@ repository (`git commit`):
 > > {: .bash}
 > > Now the files are ready to commit. You can check that using `git status`. If you are ready to commit use:
 > > ~~~
-> > $ git commit -m "Wrote down my plans to start a base on Venus"
+> > $ git commit -m "Write plans to start a base on Venus"
 > > ~~~
 > > {: .bash}
 > > ~~~
 > > [master cc127c2]
-> >  Wrote down my plans to start a base on venus
+> >  Write plans to start a base on Venus
 > >  2 files changed, 2 insertions(+)
 > >  create mode 100644 venus.txt
 > > ~~~
@@ -713,11 +713,11 @@ repository (`git commit`):
 > >
 > > ~~~
 > > $ git add me.txt
-> > $ git commit -m "Updated Vlad's bio." --author="Frank N. Stein <[email protected]>"
+> > $ git commit -m "Update Vlad's bio." --author="Frank N. Stein <[email protected]>"
 > > ~~~
 > > {: .bash}
 > > ~~~
-> > [master 4162a51] Updated Vlad's bio.
+> > [master 4162a51] Update Vlad's bio.
 > > Author: Frank N. Stein <[email protected]>
 > > 1 file changed, 2 insertions(+), 2 deletions(-)
 > >
@@ -726,7 +726,7 @@ repository (`git commit`):
 > > Author: Frank N. Stein <[email protected]>
 > > Commit: Vlad Dracula <[email protected]>
 > >
-> > Updated Vlad's bio.
+> > Update Vlad's bio.
 > >
 > > commit aaa3271e5e26f75f11892718e83a3e2743fab8ea
 > > Author: Vlad Dracula <[email protected]>

_episodes/05-history.md

@@ -382,7 +382,7 @@ moving backward and forward in time becomes much easier.
 > $ nano venus.txt #input the following text: Venus is beautiful and full of love
 > $ git add venus.txt
 > $ nano venus.txt #add the following text: Venus is too hot to be suitable as a base
-> $ git commit -m "comments on Venus as an unsuitable base"
+> $ git commit -m "Comment on Venus as an unsuitable base"
 > $ git checkout HEAD venus.txt
 > $ cat venus.txt #this will print the contents of venus.txt to the screen
 > ~~~
@@ -445,7 +445,7 @@ moving backward and forward in time becomes much easier.
 > > The file has been modified. The new changes are not staged because we have not added the file.
 > >
 > > ~~~
-> > $ git commit -m "comments on Venus as an unsuitable base"
+> > $ git commit -m "Comment on Venus as an unsuitable base"
 > > ~~~
 > > {: .bash}
 > > The changes that were stagged (Venus is beautiful and full of love) have been commited. The changes that were not stagged (Venus is too hot to be suitable as a base) have not. Our local working copy is different than the copy in our local repository.

_episodes/08-collab.md

@@ -64,7 +64,7 @@ It is so a planet!
 
 ~~~
 $ git add pluto.txt
-$ git commit -m "Some notes about Pluto"
+$ git commit -m "Add notes about Pluto"
 ~~~
 {: .bash}
 

_episodes/09-conflict.md

@@ -55,12 +55,12 @@ and then push the change to GitHub:
 
 ~~~
 $ git add mars.txt
-$ git commit -m "Adding a line in our home copy"
+$ git commit -m "Add a line in our home copy"
 ~~~
 {: .bash}
 
 ~~~
-[master 5ae9631] Adding a line in our home copy
+[master 5ae9631] Add a line in our home copy
  1 file changed, 1 insertion(+)
 ~~~
 {: .output}
@@ -103,12 +103,12 @@ We can commit the change locally:
 
 ~~~
 $ git add mars.txt
-$ git commit -m "Adding a line in my copy"
+$ git commit -m "Add a line in my copy"
 ~~~
 {: .bash}
 
 ~~~
-[master 07ebc69] Adding a line in my copy
+[master 07ebc69] Add a line in my copy
  1 file changed, 1 insertion(+)
 ~~~
 {: .output}
@@ -227,12 +227,12 @@ Changes to be committed:
 {: .output}
 
 ~~~
-$ git commit -m "Merging changes from GitHub"
+$ git commit -m "Merge changes from GitHub"
 ~~~
 {: .bash}
 
 ~~~
-[master 2abf2b1] Merging changes from GitHub
+[master 2abf2b1] Merge changes from GitHub
 ~~~
 {: .output}
 
@@ -347,12 +347,12 @@ consider one of these approaches to reducing them:
 > >
 > > ~~~
 > > $ git add mars.jpg
-> > $ git commit -m "Picture of Martian surface"
+> > $ git commit -m "Add picture of Martian surface"
 > > ~~~
 > > {: .bash}
 > >
 > > ~~~
-> > [master 8e4115c] Picture of Martian surface
+> > [master 8e4115c] Add picture of Martian surface
 > >  1 file changed, 0 insertions(+), 0 deletions(-)
 > >  create mode 100644 mars.jpg
 > > ~~~
@@ -519,7 +519,7 @@ consider one of these approaches to reducing them:
 > > |1    | Update local      | `git pull origin master`                     |
 > > |2    | Make changes      | `echo 100 >> numbers.txt`                    |
 > > |3    | Stage changes     | `git add numbers.txt`                        |
-> > |4    | Commit changes    | `git commit -m "Added 100 to numbers.txt"`   |
+> > |4    | Commit changes    | `git commit -m "Add 100 to numbers.txt"`     |
 > > |5    | Update remote     | `git push origin master`                     |
 > > |6    | Celebrate!        | `AFK`                                        |
 > >