Resolve "use Markdown for changelog"

CHANGELOG.md

+# Changelog of Pmodules
+
+## Unreleased
+
+**Added features:**
+
+**Changed:**
+
+**Deprecated:**
+
+**Removed:**
+
+**Fixed bugs:**
+
+
+## Version 1.0.0rc6
+
+**Added features:**
+
+- Support for shell `sh` added (#86, #90).
+- Support added for a wildcard (`.*`) version as argument to `modbuild` (#78)
+
+**Fixed bugs:**
+
+- Handle empty list of be installed shared libraries fixed (#89).
+- Broken 'module load'  with (T)CSH fixed (#88).
+- prepend instead of append Pmodules bin directory to `PATH` (#87).
+- Bugs in bootstrapping Pmodules fixed (#82)
+
+
+## Version 1.0.0rc5 (since 1.0.0rc2)
+
+**Added features:**
+
+- log `module load` commands to system logger (#80)
+
+
+**Changed:**
+
+- The argument passed with the `--system` is not any more a synonym for kernel of the system a build process is running on. It now defines a target operating system like RHEL6, macOS1014 etc (#72).
+
+
+**Deprecated:**
+
+- calling `pbuild::make_all` in a build-script is now deprecate
+
+**Fixed bugs:**
+
+- Bugs fixed in printing load hints (#48, #49)
+- Several bugs in build-systen and `modulecmd` fixed.
+- `--with` option of sub-command search now accepts a comma separated list of strings
+- `PMODULES_ENV` is exported only on content changes
+
+
+## 1.0.0rc4
+  - never tagged
+  
+## 1.0.0rc3
+  - never tagged

CHANGES

-Changes in version 1.0.0rc5 (since 1.0.0rc2)
-  - build-system
-    * lot of cleanup, refactoring and bugfixes
-    * '.*' is now a valid version argument
-    * 'system' isn't a synonym for OS/kernel any more. It defines a target operating system like RHEL6, macOS1014. 
-    * checks for supported system, OS and compiler
-    * compute default for the number of parallel make jobs
-    * calling pbuild::make_all in a build-script is now deprecate
-
-  - modulecmd
-    * --with option of sub-command search now accepts a comma separated list of strings
-    * better load hints
-    * log modules loaded to syslog
-    * PMODULES_ENV is exported only on content changes
-    * bugfixes and cleanup
-
-1.0.0rc4
-  - never tagged
-1.0.0rc3
-  - never tagged