add links from wikimedia for the figures in the metabolic network blog post

Author: TolisChal

_posts/2021-09-06-metabolic-networks.md

@@ -62,7 +62,7 @@ many other reactions. Together all these metabolites and reactions form a _metab
 network_.
 
 <center>
-    <img src="https://github.com/GeomScale/geomscale.github.io/blob/gh-pages/_posts/figures/small_recon_net_2.png"><br>
+    <img src="https://upload.wikimedia.org/wikipedia/commons/f/f0/Small_recon_net.png"><br>
     A small fragment of the human metabolic network (Recon1)
 </center>
 
@@ -123,7 +123,7 @@ The reaction 3DSPHR participates in [sphingolipid metabolism](https://www.kegg.j
 while the reaction TYMSULT is related to the protein-tyrosine sulfotransferase [activity](https://www.kegg.jp/entry/R02586).
 
 <center>
-    <img src="https://github.com/GeomScale/geomscale.github.io/blob/gh-pages/_posts/figures/FBA_fluxes_fba_r_2.png"><br>
+    <img src="https://upload.wikimedia.org/wikipedia/commons/f/f0/FBA_fluxes.png"><br>
 </center>
 
 For both GK1 and CTPS2, FBA implies that the fluxes increase when the virus biomass takes its maximum possible value.
@@ -183,12 +183,13 @@ two vertical dotted lines the two fluxes that I previously computed with FBA. Ne
 with the average fluxes we get from `dingo`'s sampling routines.
 
 <center>
-    <img src="https://github.com/GeomScale/geomscale.github.io/blob/gh-pages/_posts/figures/density_flux_TYMSULT_fba_2.png"><br>
-    <img src="https://github.com/GeomScale/geomscale.github.io/blob/gh-pages/_posts/figures/density_flux_3DSPHR_fba_2.png"><br>
-    <img src="https://github.com/GeomScale/geomscale.github.io/blob/gh-pages/_posts/figures/density_flux_ctps2_fba_2.png"><br>
-    <img src="https://github.com/GeomScale/geomscale.github.io/blob/gh-pages/_posts/figures/density_flux_gk1_fba_2.png"><br>
+    <img src="https://upload.wikimedia.org/wikipedia/commons/b/b4/Density_flux_TYMSULT.png"><br>
+    <img src="https://upload.wikimedia.org/wikipedia/commons/a/a6/Density_flux_3DSPHR.png"><br>
+    <img src="https://upload.wikimedia.org/wikipedia/commons/d/da/Density_flux_ctps2.png"><br>
+    <img src="https://upload.wikimedia.org/wikipedia/commons/b/b5/Density_flux_gk1.png"><br>
 </center>
 
+
 The blue density is computed by human's biomass-optimized states, while the red density is computed
 by virus-optimized states. The fluxes with a higher value on the y-axis in the plot are
 more possible to be selected by the metabolic network.
@@ -221,7 +222,7 @@ values of TYMSULT are not zero here, as we noticed in the corresponding probabil
 densities, but they are both much smaller than the other flux values.
 
 <center>
-    <img src="https://github.com/GeomScale/geomscale.github.io/blob/gh-pages/_posts/figures/average_fluxes_sampling_r.png"><br>
+    <img src="https://upload.wikimedia.org/wikipedia/commons/b/b0/Average_fluxes.png"><br>
 </center>
 
 To summarize, flux sampling could agree or disagree with FBA about the flux values. In