Move deps from tox to requirements file

Issue-ID: NONRTRIC-771
Change-Id: I20530584e0038c8e954f465254b1ef61177f7328
Signed-off-by: halil.cakal <halil.cakal@est.tech>
diff --git a/tox.ini b/tox.ini
index e09164c..8a3aaa6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -49,13 +49,7 @@
 [testenv:docs]
 whitelist_externals = echo
 basepython = python3.8
-deps =
-    sphinx
-    sphinx-rtd-theme
-    sphinxcontrib-httpdomain
-    sphinxcontrib-redoc
-    recommonmark
-    lfdocs-conf
+deps = -r{toxinidir}/docs/requirements-docs.txt
 commands =
     sphinx-build -W -b html -n -d {envtmpdir}/doctrees ./docs/ {toxinidir}/docs/_build/html
     echo "Generated docs available in {toxinidir}/docs/_build/html"
@@ -63,10 +57,6 @@
 [testenv:docs-linkcheck]
 skipsdist = true
 basepython = python3.8
-deps = sphinx
-       sphinx-rtd-theme
-       sphinxcontrib-httpdomain
-       sphinxcontrib-redoc
-       recommonmark
-       lfdocs-conf
-commands = sphinx-build -W -b linkcheck -d {envtmpdir}/doctrees ./docs/ {toxinidir}/docs/_build/linkcheck
+deps = -r{toxinidir}/docs/requirements-docs.txt
+commands =
+    sphinx-build -W -b linkcheck -d {envtmpdir}/doctrees ./docs/ {toxinidir}/docs/_build/linkcheck