Update README.md with latest presentations.

README.md

@@ -32,18 +32,18 @@ Details for the next session:
 
 | Time  | Subject                                                                                | Teacher           | Contents                  |
 | ----- | -----------------                                                                      | ----------------- | ------------------------- |
-| 10:00 | [Introduction](/uploads/ccbce60d8d17dd5e9d7949d91cc20a57/introduction.pdf)             | Mihai Lefter      | Welcome, version control introduction |
+| 10:00 | [Introduction](/uploads/c751916e71cc02c026491fad6c171a7d/introduction.pdf)             | Mihai Lefter      | Welcome, version control introduction |
 | 10:30 | [Git basics](/uploads/5c35a9ecd72033b42ef55b602f6cb548/20170906_-_git-course_-_git-basics.pdf) | Wibowo Arindrarto | Basic Git command line flow |
 | 11:15 | [Practical](/uploads/d56ee5edaeca415c5430b385750a89de/basics_handouts.pdf)             |                   |                           |
 | 12:00 | Lunch                                                                                  |                   |                           |
 | 13:00 | [Collaboration: remote repositories](/uploads/a189f6a373afac0509d96812d7a2b49a/remotes.pdf)   | Jonathan Vis   | Sharing and collaborating via remotes |
 | 13:45 | [Practical](/uploads/286d7abb800c6f3f1540a49a6aefd25b/remotes_handouts.pdf)             |                   |                           |
 | 14:15 | Break                                                                                  |                   |                           |
-| 14:30 | [Collaboration: combining changes by merging](/uploads/1bc6dc39f8c0234264b3efbbd596ccbe/merging.pdf)  | Mihai Lefter   | Commit graph, merging, resolving merge conflicts |
-| 15:15 | [Practical](/uploads/9455ef406dfeb0e3c365c015965cd899/merging_handouts.pdf)            |                   |                           |
+| 14:30 | [Collaboration: combining changes by merging](/uploads/daec1d922f0bfe036adfea260dba26b0/merging.pdf)  | Mihai Lefter   | Commit graph, merging, resolving merge conflicts |
+| 15:15 | [Practical](/uploads/d8fb514d9181aed85ff2843ce80ec4d0/merging_handouts.pdf)            |                   |                           |
 | 15:45 | Break                                                                                  |                   |                           |
-| 16:00 | [Extras]()  | Mihai Lefter   | GitLab, GitHub, Markdown, ... |
-| 16:30 | [Practical]()            |                   |                           |
+| 16:00 | [Extras](/uploads/6421469e8b44778f7c57958ba5f36171/extras.pdf)  | Mihai Lefter   | GitLab and Markdown. |
+| 16:30 | [Practical](/uploads/3cde4b0450bf749bb5b9a7954adb8f33/extras_handouts.pdf)            |                   |                           |
 | 17:00 | Questions, closing                                                                     |                   |                           |