Wiki Link Updates (#4699)

##### Summary
<!--- Describe the change below, including rationale and design decisions -->
Replaces links to wiki pages with links to the respective markdown files in the repo. The files with the updates in this PR are not MD files. 

Fixes #4650 
<!--- HINT: Include "Fixes #nnn" if you are fixing an existing issue -->

##### Component Name
<!--- Write the short name of the module or plugin below -->

##### Additional Information
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<!--- A step-by-step reproduction of the problem is helpful if there is no related issue -->

<!--- Paste log output below, e.g. before and after your change -->
```paste below

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1 files changed, 6 insertions, 6 deletions

diff --git a/HISTORICAL_CHANGELOG.md b/HISTORICAL_CHANGELOG.md
index c9d66e9362..3e7688f33d 100644
--- a/HISTORICAL_CHANGELOG.md
+++ b/HISTORICAL_CHANGELOG.md
@@ -127,7 +127,7 @@ netdata (1.6.0) - 2017-03-20
    menu on the dashboard.
 
    For more information check:
-   https://github.com/netdata/netdata/wiki/monitoring-ephemeral-nodes
+   https://github.com/netdata/netdata/tree/master/streaming#monitoring-ephemeral-nodes
 
  * monitoring ephemeral containers and VM guests
 
@@ -135,7 +135,7 @@ netdata (1.6.0) - 2017-03-20
    disk metrics, disabling automatically their alarms too.
 
    For more information check:
-   https://github.com/netdata/netdata/wiki/monitoring-ephemeral-containers
+   https://github.com/netdata/netdata/tree/master/collectors/cgroups.plugin#monitoring-ephemeral-containers
 
  * apps.plugin ported for FreeBSD
 
@@ -150,7 +150,7 @@ netdata (1.6.0) - 2017-03-20
    and web sites!
 
    For more information check:
-   https://github.com/netdata/netdata/wiki/The-spectacles-of-a-web-server-log-file
+   https://github.com/netdata/netdata/blob/master/collectors/python.d.plugin/web_log#web_log
 
  * backends
 
@@ -176,7 +176,7 @@ netdata (1.6.0) - 2017-03-20
    It also supports alarms (including the number of sensors in critical state).
 
    For more information, check:
-   https://github.com/netdata/netdata/wiki/monitoring-IPMI
+   https://github.com/netdata/netdata/tree/master/collectors/freeipmi.plugin
 
  * new plugins
 
@@ -446,7 +446,7 @@ netdata (1.3.0) - 2016-08-28
  required to be installed on a system to allow it work.
  For more information, please check the installation page:
 
- https://github.com/netdata/netdata/wiki/Installation
+ https://github.com/netdata/netdata/tree/master/installer#installation
 
  In detail:
 
@@ -459,7 +459,7 @@ netdata (1.3.0) - 2016-08-28
    netdata now has a poweful health monitoring system embedded.
    Please check the wiki page:
 
-   https://github.com/netdata/netdata/wiki/health-monitoring
+   https://github.com/netdata/netdata/tree/master/health
 
  * netdata has badges!